In addition, a man's love (4)
I believe the answer is:
also
'in addition' is the definition.
(synonyms)
'a man's love' is the wordplay.
'a man's' becomes 'Als' (man's name).
'love' becomes 'o' (love means zero in tennis).
'als'+'o'='ALSO'
(Other definitions for also that I've seen before include "What's more" , "Old" , "Item" , "item's rarely used now for this" , "Furthermore" .)