After party starts to seek some sleep (4)
I believe the answer is:
doss
'sleep' is the definition.
(thesaurus)
'after party starts to seek some' is the wordplay.
'after' says to put letters next to each other.
'party' becomes 'do' (do is a kind of party).
'starts to' says to take the initial letters.
The first letters of 'seek some' is 'ss'.
'do'+'ss' is 'DOSS'.
(Other definitions for doss that I've seen before include "easily accomplished" , "Sleep like a tramp" , "Sleep - sleeping place" , "Sleep somewhere convenient" , "In slang, sleep on sods" .)