Thinks of love and languishes (6)
I believe the answer is:
opines
'thinks' is the definition.
(I've seen this in another clue)
'love and languishes' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'and' says to put letters next to each other.
'languishes' becomes 'pines' ('pine' can be a synonym of 'languish').
'o'+'pines'='OPINES'
'of' is the link.
(Other definitions for opines that I've seen before include "'Supposes, considers (6)'" , "Offers views" , "suspects" , "Expresses one's view" , "Provides a view" .)