Welcome to the party! (9)
I believe the answer is:
reception
I believe this is a double definition.
'welcome' is the first definition.
(thesaurus)
'the party' is the second definition.
(reception is a kind of party)
'to' acts as a link.
(Other definitions for reception that I've seen before include "drinks party" , "Welcome" , "Formal function" , "signal quality" , "A social event" .)