Model in a state exits opening show (7)
I believe the answer is:
matinee
'show' is the definition.
(matinee is a kind of show)
'model in a state exits opening' is the wordplay.
'model' becomes 'T' (Ford Model T car).
'in' is an insertion indicator.
'a state' becomes 'maine' (US state).
'opening' suggests taking the first letters.
The initial letter of 'exits' is 'e'.
't' going within 'maine' is 'matine'.
'matine'+'e'='MATINEE'
(Other definitions for matinee that I've seen before include "early "performance"" , "After lunch, show" , "Performance held in the afternoon" , "Play, perhaps" , "Afternoon performance (of play etc)" .)