Old car restricted by minimal leg room (7)
I believe the answer is:
allegro
'old car' is the definition.
(I've seen this before)
'restricted by minimal leg room' is the wordplay.
'restricted by' indicates a hidden word.
'ALLEGRO' is hidden within 'minimal leg room'.
(Other definitions for allegro that I've seen before include "Quickly (in music)" , "In music, fast and lively" , "Scored at a brisk speed" , "Brisk and lively tempo, musically" , "To be performed in brisk style" .)