What does the cryptic crossword clue "Period with insects, when you’re having fun … ? (4,5)" mean?

The wordplay uses a charade (building blocks). TIME (synonym="period") + FLIES (synonym="FLIES") = TIMEFLIES The answer is TIMEFLIES.

Period with insects, when you’re having fun … ? (4,5)

Guardian Cryptic #29555 | 1 Down | 2024-12-02 flower