Work on child's plaything for a bit (6)
I believe the answer is:
dollop
'a bit' is the definition.
(thesaurus)
'work on child's plaything' is the wordplay.
'work' becomes 'op' (abbreviation for opus).
'on' means one lot of letters go next to another.
'child's plaything' becomes 'doll' (I've seen this before).
'op' after 'doll' is 'DOLLOP'.
'for' acts as a link.
(Other definitions for dollop that I've seen before include "Shapeless mass or lump" , "Large shapeless lump" , "great lump" , "Small shapeless mass" , "Small measure, of mash say" .)