Go to sleep? No - party's very loud (3,3)
I believe the answer is:
nod off
'go to sleep?' is the definition.
('nod off' can be a synonym of 'go to sleep')
'no party's very loud' is the wordplay.
'party' becomes 'do' (do is a kind of party).
'very loud' becomes 'ff' (musical abbreviation).
'no'+'do'+'ff'='NOD OFF'
(Other definitions for nod off that I've seen before include "Fall asleep with head movement?" , "Fall asleep with drooping head" , "Become drowsy with moving cranium" , "'Fall asleep (3,3)'" , "Go to sleep with head movements" .)