Expression of surprise about a vehicle seen in the capital (6)
I believe the answer is:
havana
'the capital' is the definition.
(Havana is an example)
'expression of surprise about a vehicle' is the wordplay.
'expression of surprise' becomes 'ha'.
'about' is an insertion indicator.
'vehicle' becomes 'van' (van is a kind of vehicle).
'a'+'van'='avan'
'ha' going around 'avan' is 'HAVANA'.
'seen in' is the link.
(Other definitions for havana that I've seen before include "island capital" , "Capital of Cuba" , "Cuba's capital" , "Cuban capital - cigar" , "Smoke" .)