SEAL gets in training (6)
I believe the answer is:
signet
'seal' is the definition.
(I know that signet is a type of seal)
'gets in training' is the wordplay.
'training' is an anagram indicator (to train can mean to grow something into a shape).
'gets'+'in'='getsin'
'getsin' anagrammed gives 'SIGNET'.
(Other definitions for signet that I've seen before include "Little seal" , "Ingest (anag)" , "Tuft of hanging threads" , "Small seal set in a ring" , "Small seal, on ring perhaps" .)