A vehicle seen in the middle of that capital (6)
I believe the answer is:
havana
'capital' is the definition.
(Havana is an example)
'a vehicle seen in the middle of that' is the wordplay.
'vehicle' becomes 'van' (van is a kind of vehicle).
'seen in' means one lot of letters goes inside another.
'the middle of' indicates the central letters.
The middle letters of 'that' are 'ha'.
'a'+'van'='avan'
'avan' going within 'ha' is 'HAVANA'.
(Other definitions for havana that I've seen before include "city" , "Cuba's capital" , "Caribbean capital" , "Cuban capital - cigar" , "Fine cigar" .)