What does the cryptic crossword clue "Allegation, one that’s harboured by reticent type (5)" mean?

The wordplay uses a container (one word inside another). I (synonym="one") in CLAM (synonym=""reticent type"") = CLAIM The answer is CLAIM.

Allegation, one that’s harboured by reticent type (5)

Guardian Cryptic #29388 | 21 Across | 2024-05-21 flower