Demanding toy car (7)
I believe the answer is:
hardtop
'car' is the definition.
(hardtop is a kind of car)
'demanding toy' is the wordplay.
'demanding' becomes 'hard' (associated in meaning).
'toy' becomes 'top' (top is a kind of toy).
'hard'+'top'='HARDTOP'
(Other definitions for hardtop that I've seen before include "Type of car with removable roof" , "Sort of car" , "Car with a rigid top" , "Style of car" , "Non-convertible car" .)