Watch actor in church: good on-line clip! (7,3)
I believe the answer is:
clothes peg
'on-line clip' is the definition.
(clip used on a washing line)
'watch actor in church good' is the wordplay.
'watch' becomes 'lo'.
'actor' becomes 'thesp' (short for thespian, term for an actor).
'in' indicates putting letters inside.
'church' becomes 'CE' (abbreviation for Church of England).
'good' becomes 'g' (abbreviation).
'lo'+'thesp'='lothesp'
'lothesp' placed into 'ce' is 'clothespe'.
'clothespe'+'g'='CLOTHES-PEG'
(Other definitions for clothes peg that I've seen before include "Fastener for washing line" , "on-line clip?" , "one stuck on the line?" , "Device to clip laundry to line" .)