Working party's tense attempt to see church (4,5)
I believe the answer is:
task force
'working party's' is the definition.
(I've seen this before)
'tense attempt to see church' is the wordplay.
'tense' becomes 't' (grammatical abbreviation).
'attempt to see' becomes 'ask for' (ask to see someone).
'church' becomes 'CE' (abbreviation for Church of England).
't'+'askfor'+'ce'='TASK-FORCE'
(Other definitions for task force that I've seen before include "specially-trained unit" , "Group assembled for a particular undertaking" , "working party" , "Special work group" , "specially organised unit" .)