Margin call accepted by loud European (6)
I believe the answer is:
fringe
'margin' is the definition.
(thesaurus)
'call accepted by loud european' is the wordplay.
'call' becomes 'ring' (telephone call).
'accepted by' means one lot of letters goes inside another (inserted letters are accepted).
'loud' becomes 'f' (short for forte - 'loud' in music).
'european' becomes 'E' (abbreviation e.g. EU).
'f'+'e'='fe'
'ring' inserted into 'fe' is 'FRINGE'.
(Other definitions for fringe that I've seen before include "Tasselled edging" , "Finger (anag.)" , "Border; not mainstream" , "Thrum" , "(Tasselled) border" .)