Seat is adjusted for forty winks? (6)
I believe the answer is:
siesta
'forty winks?' is the definition.
(siesta is a kind of forty winks)
'seat is adjusted' is the wordplay.
'adjusted' indicates anagramming the letters.
'seat'+'is'='seatis'
'seatis' anagrammed gives 'SIESTA'.
'for' is the link.
(Other definitions for siesta that I've seen before include "Spanish afternoon activity" , "Afternoon nap in a warm climate" , "Diurnal nap in Spain" , "PM snooze" , "Early afternoon nap" .)