Imposed objective, packing on behalf of church (8)
I believe the answer is:
enforced
'imposed' is the definition.
('enforce' can be a synonym of 'impose')
'objective packing on behalf of church' is the wordplay.
'objective' becomes 'end' (I've seen this before).
'packing' is an insertion indicator.
'on behalf of' becomes 'for' (I've seen this before).
'church' becomes 'ce' (abbreviation for Church of England).
'for'+'ce'='force'
'end' placed around 'force' is 'ENFORCED'.
(Other definitions for enforced that I've seen before include "Imposed" , "'Compelled observance of, a law say (8)'" , "Compulsory" , "Ensured observance of rules" , "Taken effect" .)