Collapsed around part of church (4)
I believe the answer is:
apse
'part of church' is the definition.
(part of a church building)
'collapsed around' is the wordplay.
'around' indicates the answer is hidden within the clue.
'APSE' is hidden in the letters of 'collapsed'.
(Other definitions for apse that I've seen before include "room for an altar" , "Peas (anag) - found in church" , "where praetor sat" , "Church area" , "Recess at east end of church" .)