Outgoing text sent off about partygoer (9)
I believe the answer is:
extravert
'outgoing' is the definition.
(I've seen this before)
'text sent off about partygoer' is the wordplay.
'sent off' indicates an anagram.
'about' means one lot of letters goes inside another.
'partygoer' becomes 'raver' (I've seen this before).
'text' is an anagram of 'extt'.
'extt' placed around 'raver' is 'EXTRAVERT'.
(Other definitions for extravert that I've seen before include "High-spirited" , "Very sociable" , "Outward-looking" , "Outgoing" , "Socially confident sort" .)