Fine with children's game (5)
I believe the answer is:
wispy
'fine' is the definition.
(thesaurus)
'with children's game' is the wordplay.
'with' becomes 'w' (abbreviation).
'children's game' becomes 'ispy' (I've seen this before).
'w'+'ispy'='WISPY'
(Other definitions for wispy that I've seen before include "Straggly" , "Slender and delicate" , "In thin strands" , "Light and fine in texture" , "Flimsy" .)