Is lying back on the seat prepared to have a snooze (6)
I believe the answer is:
siesta
'a snooze' is the definition.
(I know that siesta is a type of snooze)
'is lying back on the seat prepared' is the wordplay.
'lying back' says the letters should be written in reverse.
'on' says to put letters next to each other.
'prepared' is an anagram indicator.
'is' in reverse letter order is 'si'.
'seat' is an anagram of 'esta'.
'si'+'esta'='SIESTA'
'to have' acts as a link.
(Other definitions for siesta that I've seen before include "Early afternoon nap" , "An afternoon nap in Spain" , "Afternoon snooze" , "Rest of Spain" , "Afternoon break" .)