Music-maker's old vehicle, popular one (7)
I believe the answer is:
ocarina
'music-maker's' is the definition.
(type of musical instrument)
'old vehicle popular one' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'vehicle' becomes 'car' (car is a kind of vehicle).
'popular' becomes 'in' ('in' can mean trendy).
'one' becomes 'a' (a thing is one thing).
'o'+'car'+'in'+'a'='OCARINA'
(Other definitions for ocarina that I've seen before include "Simple wind instrument" , "toy instrument" , "Play a musical toy in the ICA, Nora" , "Egg-shaped wind instrument with finger holes" , "Primitive wind instrument" .)