Alliance has a complaint against the French (6)
I believe the answer is:
league
'alliance' is the definition.
(I've seen this before)
'a complaint against the french' is the wordplay.
'a complaint' becomes 'ague' (ague is a kind of disease).
'against' says to put letters next to each other.
'the french' becomes 'le' ('the' in French).
'ague' after 'le' is 'LEAGUE'.
'has' is the link.
(Other definitions for league that I've seen before include "Association for a common purpose" , "some mileage?" , "distance at sea" , "Coalition" , "Former measure, approx. three miles" .)