Fond of a party? Then call! (7)
I believe the answer is:
adoring
'fond' is the definition.
(synonyms)
'a party? then call' is the wordplay.
'party?' becomes 'do' (do can informally mean a party).
'then' says to put letters next to each other.
'call' becomes 'ring' (telephone call).
'a'+'do'+'ring'='ADORING'
'of' is the link.
(Other definitions for adoring that I've seen before include "Extravagantly indulgent" , "Passionate" , "Worshipful" , "Giving great love" , "Really getting into" .)