Her love was for Leander (4)
I believe the answer is:
hero
'for leander' is the definition.
The definition suggests a singular noun which matches the answer.
'her love' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'her'+'o'='HERO'
'was' is the link.
Can you help me to learn more?
(Other definitions for hero that I've seen before include "eg Hercules" , "Man of outstanding courage" , "Leander's suitor" , "Chief good guy in a book or film" , "Principal male character in a play, movie, novel or poem" .)