Baby seal (3)
'baby seal?' is the definition.
(I've seen this in another clue)
'seal?' is the wordplay.
I cannot really understand how this works, but
'seal?' could be 'sign' (seal is a kind of sign) and 'sign' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for signet that I've seen before include "Kind of ring with seal" , "Little seal" , "Small seal - type of ring" , "'Seal, on a ring say (6)'" , "Small seal, on ring perhaps" .)
'baby seal' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for pup that I've seen before include "Produce litter" , "Small palindromic dog" , "Young animal" , "Canine young" , "Whelp" .)