Note about spies in party, perhaps (6)
I believe the answer is:
social
'party perhaps' is the definition.
(social can mean a party or event)
'note about spies' is the wordplay.
'note' becomes 'sol' (musical note as in do-re-mi-fa-sol-la-ti).
'about' means one lot of letters goes inside another.
'spies' becomes 'CIA' (Central Intelligence Agency).
'sol' enclosing 'cia' is 'SOCIAL'.
'in' is the link.
(Other definitions for social that I've seen before include "Gregarious or neighbourly" , "Enjoying companionship" , "Living in an organised community in Licosa" , "Seeking companionship" , "Relating to human groups" .)