Case big church hiding current member of government (7,8)
I believe the answer is:
cabinet minister
'member of government' is the definition.
(I've seen this before)
'case big church hiding current' is the wordplay.
'case' becomes 'cabinet' (I've seen this before).
'big church' becomes 'minster'.
'hiding' indicates putting letters inside.
'current' becomes 'I' (symbol for electric current).
'minster' going around 'i' is 'minister'.
'cabinet'+'minister'='CABINET MINISTER'
(Other definitions for cabinet minister that I've seen before include "went down to provide 22 24 [WHISKY GALORE] - with 17d" , "May perhaps" , "member of government" , "senior politician" , "high-ranking member?" .)