Sweetheart gets nothing achieved (5,3)
I believe the answer is:
loved one
'sweetheart' is the definition.
(I've seen this before)
'nothing achieved' is the wordplay.
'nothing' becomes 'love' (love means zero in tennis).
'achieved' becomes 'done' (I've seen this before).
'love'+'done'='LOVED ONE'
'gets' is the link.
(Other definitions for loved one that I've seen before include "Precious person" , "Sweetheart" .)