Impressive church car halted in crash (9)
I believe the answer is:
cathedral
'impressive church' is the definition.
'cathedral' can be an answer for 'church' (cathedral is a kind of church). I am not certain of the 'impressive' bit.
'car halted in crash' is the wordplay.
'in crash' indicates an anagram.
'car'+'halted'='carhalted'
'carhalted' anagrammed gives 'CATHEDRAL'.
Can you help me to learn more?
(Other definitions for cathedral that I've seen before include "Principal 2 down of diocese" , "Where one worships" , "See 6" , "Principle church of diocese" , "Principal diocesan church" .)