Almost time — for bedtime (5)
I believe the answer is:
night
'bedtime' is the definition.
'almost time' is the wordplay.
'almost' becomes 'nigh' (nigh can mean almost or nearly).
'time' becomes 't' (abbreviation).
'nigh'+'t'='NIGHT'
'for' acts as a link.
(Other definitions for night that I've seen before include "For most, the time for sleep" , "Time between days" , "8d [DARKNESS]" , "See 8" , "A Hard Day's (the Beatles)" .)