Offspring's hand put in tin (5)
I believe the answer is:
spawn
'offspring's' is the definition.
(I've seen this before)
'hand put in tin' is the wordplay.
'hand' becomes 'paw' (synonyms).
'put in' is an insertion indicator.
'tin' becomes 'Sn' (Sn is the chemical symbol for tin).
'paw' put into 'sn' is 'SPAWN'.
(Other definitions for spawn that I've seen before include "Engender" , "Breed" , "(Of fish) release eggs" , "Product" , "Multiply" .)