Two from French union church (5)
I believe the answer is:
deuce
'two' is the definition.
(synonyms)
'from french union church' is the wordplay.
'from french' becomes 'de' (French for 'from').
'union' becomes 'u' (common abbreviation as in 'Trades Union Congress').
'church' becomes 'ce' (abbreviation for Church of England).
'de'+'u'+'ce'='DEUCE'
(Other definitions for deuce that I've seen before include "Dickens" , "Level of tennis" , "score at Wimbledon?" , "Two in cards or dice" , "A two in playing cards" .)