Son had fun with toys spread out (7)
I believe the answer is:
splayed
'spread out' is the definition.
(I've seen this before)
'son had fun with toys' is the wordplay.
'son' becomes 's'.
'had fun with toys' becomes 'played'.
's'+'played'='SPLAYED'
(Other definitions for splayed that I've seen before include "with legs apart" , "Turned out" , "Spread apart" .)