Wedding attendant is French male in bar (4,3)
I believe the answer is:
best man
'wedding attendant' is the definition.
(I've seen this before)
'is french male in bar' is the wordplay.
'is french' becomes 'est' ('is' in French).
'male' becomes 'm' (common abbreviation).
'in' means one lot of letters goes inside another.
'bar' becomes 'ban' (bar can mean to ban or prohibit).
'est'+'m'='estm'
'estm' inserted inside 'ban' is 'BEST MAN'.
(Other definitions for best man that I've seen before include "Principal groomsman at a wedding" , "The groom's right-hand supporter" , "Bridegroom's friend" , "The groom's assistant at a wedding" , "Supporting male actor at a wedding" .)