What does the cryptic crossword clue "Times includes set classifications by birth (3,6)" mean?

The wordplay uses a container (one word inside another). GROUP (synonym="‘set’") in AGES (synonym="times’") = AGEGROUPS The answer is AGEGROUPS.

Times includes set classifications by birth (3,6)

Guardian Cryptic #29514 | 24 Across | 2024-10-15 flower