Hero of old seeing a doomed lover accepting kiss (9)
I believe the answer is:
alexander
'hero of old' is the definition.
(Alexander the Great)
'a doomed lover accepting kiss' is the wordplay.
'doomed lover' becomes 'Leander' (Greek mythology).
'accepting' is an insertion indicator (inserted letters are accepted).
'kiss' becomes 'x' (X can represent a kiss).
'leander' placed around 'x' is 'lexander'.
'a'+'lexander'='ALEXANDER'
'seeing' is the link.
(Other definitions for alexander that I've seen before include "A Great king of old Macedon" , "cant compare with the British Grenadier" , "band-leader" , "Sandy" , "Conquering king of Macedonia" .)