What does the cryptic crossword clue "What is 2+5 if you subtract 1 at the start? (4)" mean?

The definition is "What". The wordplay uses a cryptic definition. Cryptic definition The answer is EVEN.

What is 2+5 if you subtract 1 at the start? (4)

Independent Cryptic #12088 | 4 Down | 2025-07-07 flower