Unions maybe giving the French fits (7)
I believe the answer is:
leagues
'unions' is the definition.
(I know this)
'giving the french fits' is the wordplay.
'giving' means one lot of letters go next to another.
'the french' becomes 'le' ('the' in French).
'fits' becomes 'agues' (I've seen this in another clue).
'le' next to 'agues' is 'LEAGUES'.
'maybe' is the link.
(Other definitions for leagues that I've seen before include "Groups" , "Unions" , "Old units of length" , "Alliance" , "measures" .)