Leaders of British union inspired by hackneyed commendation (7)
I believe the answer is:
tribute
'commendation' is the definition.
(tribute is a kind of commendation)
'leaders of british union inspired by hackneyed' is the wordplay.
'leaders of' says to take the initial letters.
'inspired by' is an insertion indicator.
'hackneyed' becomes 'trite' (synonyms).
The initial letters of 'british union' is 'bu'.
'bu' put into 'trite' is 'TRIBUTE'.
(Other definitions for tribute that I've seen before include "Statement of admiration" , "Compliment" , "Payment from dependent state (historical)" , "Nice words" , "Rebut it as mark of respect" .)