What does the cryptic crossword clue "It's not easy catching variety, American counterpart of 24 (7)" mean?

The wordplay uses a container (one word inside another). VAR (synonym="variety") in HARD (synonym="not easy") = HARVARD The answer is HARVARD.

It's not easy catching variety, American counterpart of 24 (7)

Guardian Cryptic #29310 | 21 Down | 2024-02-20 flower