Vehicle seen by people in opera (6)
I believe the answer is:
carmen
'opera' is the definition.
(I've seen this before)
'vehicle seen by people' is the wordplay.
'vehicle' becomes 'car' (car is a kind of vehicle).
'seen by' is a charade indicator (letters next to each other).
'people' becomes 'men' (men are people).
'car'+'men'='CARMEN'
'in' acts as a link.
(Other definitions for carmen that I've seen before include "Bizet's great Spanish opera" , "Musical from Bizet opera" , "Spanish opera by Bizet" .)