Instrument on wheels I put in auditorium at the front (7)
I believe the answer is:
ocarina
'instrument' is the definition.
(ocarina is a kind of instrument)
'on wheels i put in auditorium at the front' is the wordplay.
'wheels' becomes 'car' (wheels can informally mean a car).
'put in' indicates putting letters inside.
'at the front' says to take the initial letters.
The first letter of 'auditorium' is 'a'.
'car'+'i'='cari'
'on' placed around 'cari' is 'ocarin'.
'ocarin'+'a'='OCARINA'
(Other definitions for ocarina that I've seen before include "dated instrument" , "Primitive wind instrument" , "Toy flute" , "Bird-shaped flute" , "music-maker" .)