In the following question, out of the four alternatives, select the alternative which is the best one word substitute for the phrase: One who is new to a profession.

Introduction / Context:
This one word substitution question focuses on vocabulary used to describe a person's level of experience. The phrase one who is new to a profession describes someone just beginning in a particular line of work, still learning the basics and lacking long term experience. Your task is to choose the single word that most accurately expresses this idea.

Given Data / Assumptions:
- Phrase: One who is new to a profession. - Options: Nuance, Pun, Tyro, Vandal. - We are looking for a noun that describes a beginner in a field.

Concept / Approach:
Tyro (also spelled tiro) is a word that means a beginner or novice in some activity, profession or field of study. It is commonly used in exam vocabulary lists to refer to someone who is just starting out. The other options refer to very different ideas: nuance is a subtle difference in meaning, pun is a play on words, and vandal is someone who deliberately damages property. Only tyro fits the description of a newcomer to a profession.

Step-by-Step Solution:
Step 1: Restate the phrase in simple words: a beginner, novice or someone newly joined to a profession. Step 2: Examine Tyro. Tyro is a noun that means a person who is new to a skill, subject or profession, exactly matching the phrase. Step 3: Examine Nuance. Nuance means a subtle difference in meaning, tone or colour, which is an abstract concept, not a person. Step 4: Examine Pun. Pun is a humorous use of words that sound similar or have more than one meaning, again not a description of a person. Step 5: Examine Vandal. Vandal refers to someone who intentionally destroys or damages property, which has nothing to do with being new to a profession.

Verification / Alternative check:
Use the correct word in a sentence: As a tyro in journalism, she still had much to learn about investigative reporting. Replacing the phrase one who is new to a profession with tyro preserves the intended meaning and makes the sentence concise. If you try to insert nuance, pun or vandal, the sentence completely changes meaning or becomes nonsensical. This confirms that tyro is the only suitable one word substitute among the options provided.

Why Other Options Are Wrong:
Nuance is wrong because it refers to a subtle shade of meaning or variation, not to a person at all. Pun is wrong because it is a type of wordplay, not a label for a beginner. Vandal is wrong because it describes someone who damages property and has no connection with professional experience level.

Common Pitfalls:
Some students may confuse tyro with similar sounding words or may not have encountered it often in daily conversation. One word substitution questions often use such words that appear more in written than in spoken English. To prepare effectively, it helps to create small groups of related terms, such as novice, tyro, beginner and neophyte, and review them regularly. Associating tyro with new recruit or trainee in a profession will help you recall it quickly during exams.

Final Answer:
The best one word substitute for “One who is new to a profession” is Tyro.