Step 1: Understanding the Concept:
An "enigma" is something mysterious, puzzling, or difficult to understand.
Step 2: Detailed Explanation:
"Elusive" means difficult to find or catch, but not exactly synonymous. "Clear" is the opposite. "Praise" means expression of approval. "Puzzle" matches the meaning of something perplexing or mysterious.
Step 3: Final Answer:
Thus, "Puzzle" is the correct synonym.