Offspring's hand caught in tin (5)
I believe the answer is:
spawn
'offspring's' is the definition.
(I've seen this before)
'hand caught in tin' is the wordplay.
'hand' becomes 'paw' ('paw' can be a synonym of 'hand').
'caught in' indicates putting letters inside.
'tin' becomes 'sn' (Sn is the chemical symbol for tin).
'paw' inserted into 'sn' is 'SPAWN'.
(Other definitions for spawn that I've seen before include "Mass of fish eggs" , "Product" , "Generate; fish eggs" , "Yield" , "Produce" .)