In due time, a refusal from the French (4)
I believe the answer is:
anon
'in due time' is the definition.
(I've seen this in another clue)
'a refusal from the french' is the wordplay.
'refusal from the french' becomes 'non' ('no' in French).
'a'+'non'='ANON'
(Other definitions for anon that I've seen before include "Writer unknown" , "Of unknown authorship" , "Soon or presently" , "Well-published writer" , "Soon; unnamed" .)