Male theologian trapped in vehicle? Hard cheese (7)
I believe the answer is:
cheddar
'hard cheese' is the definition.
(cheddar is a hard cheese)
'male theologian trapped in vehicle?' is the wordplay.
'male' becomes 'he' (he refers to a man).
'theologian' becomes 'DD' (Doctor of Divinity degree).
'trapped in' indicates putting letters inside.
'vehicle?' becomes 'car' (car is a kind of vehicle).
'he'+'dd'='hedd'
'hedd' going into 'car' is 'CHEDDAR'.
(Other definitions for cheddar that I've seen before include "Firm cheese as made in Somerset" , "Cheese; Somerset town" , "Somerset village" , "Hard 8 across" , "Mendip gorge" .)