Plentiful information on leader of union in love (8)
I believe the answer is:
generous
'plentiful' is the definition.
(thesaurus)
'information on leader of union in love' is the wordplay.
'information' becomes 'gen' (gen can informally mean information).
'on' indicates putting letters inside (as in clothing 'on' a person).
'leader of' says to take the initial letters.
'in love' becomes 'eros' (I've seen this before).
The first letter of 'union' is 'u'.
'u' put within 'eros' is 'erous'.
'gen'+'erous'='GENEROUS'
(Other definitions for generous that I've seen before include "Free" , "Lavish" , "Bountiful, unselfish" , "Willing to give unselfishly" , "Kind towards others" .)