Expensive, the French part of church (7)
I believe the answer is:
steeple
'part of church' is the definition.
(I've seen this before)
'expensive the french' is the wordplay.
'expensive' becomes 'steep' (I've seen this in another clue).
'the french' becomes 'le' ('the' in French).
'steep'+'le'='STEEPLE'
(Other definitions for steeple that I've seen before include "Tall tower with spire on top of church" , "that the church may be under" , "point" , "Jack up this?" , "Tall building" .)