Partygoer close to dancefloor, say (5)
I believe the answer is:
raver
'partygoer' is the definition.
(I've seen this before)
'close to dancefloor say' is the wordplay.
'close to' indicates one should take the final letters (the close of something is the end).
'say' becomes 'aver' (aver means to state or claim something).
The final letter of 'dancefloor' is 'r'.
'r'+'aver'='RAVER'
(Other definitions for raver that I've seen before include "Wild partygoer" , "Uninhibited person" , "one talking incoherently" , "attending acid-house party?" , "Madman" .)