Woman's first aid for puppy (5)
I believe the answer is:
whelp
'for puppy' is the definition.
(I've seen this in another clue)
'woman's first aid' is the wordplay.
'woman's first' becomes 'w' (hst letter of 'woman').
'aid' becomes 'help' (synonyms).
'w'+'help'='WHELP'
(Other definitions for whelp that I've seen before include "bear" , "Have puppies" , "A young dog or puppy" , "Young mammal" , "impudent young lad" .)