Snow? All right to seek shelter in church (4)
I believe the answer is:
coke
'snow?' is the definition.
('coke' can be a synonym of 'snow')
'all right to seek shelter in church' is the wordplay.
'all right' becomes 'ok' (synonyms).
'to seek shelter in' means one lot of letters goes inside another.
'church' becomes 'CE' (abbreviation for Church of England).
'ok' placed within 'ce' is 'COKE'.
(Other definitions for coke that I've seen before include "Fuel for heating" , "A solid fuel; a drug (abbr.)" , "Nose candy" , "something for heating" , "Carbonised fuel residue" .)