Python shelters in church (6)
I believe the answer is:
cleese
'python' is the definition.
(Monty Python member John Cleese)
'shelters in church' is the wordplay.
'shelters' becomes 'lees' (I've seen this in another clue).
'in' is an insertion indicator.
'church' becomes 'CE' (abbreviation for Church of England).
'lees' going within 'ce' is 'CLEESE'.
(Other definitions for cleese that I've seen before include "Monty Python actor" , "John - (Fawlty Towers)" , "English comic actor and writer, b. 1939" , "John --, English comedian and actor" , "John --, British comedian" .)