After end of work I quietly sleep (3)
I believe the answer is:
kip
'sleep' is the definition.
('kip' can be a synonym of 'sleep')
'after end of work i quietly' is the wordplay.
'after' says to put letters next to each other.
'end of' suggests the final letters.
'quietly' becomes 'p' (p for piano and quiet).
The final letter of 'work' is 'k'.
'k' put next to 'i' is 'ki'.
'ki'+'p'='KIP'
(Other definitions for kip that I've seen before include "Short sleep" , "Sleep, nap (colloq.)" , "Nap (slang)" , "Sleep (sl.)" , "Slumber" .)