The French in church with British star (5)
I believe the answer is:
celeb
'star' is the definition.
(I've seen this before)
'the french in church with british' is the wordplay.
'the french' becomes 'le' ('the' in French).
'in' is an insertion indicator.
'church' becomes 'CE' (Church of England).
'with' says to put letters next to each other.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'ce'+'b'='ceb'
'le' inserted inside 'ceb' is 'CELEB'.
(Other definitions for celeb that I've seen before include "Famous person (colloq.)" , "Famous person (abbr)" , "popular star" , ""Personality"" , "Household name" .)