Lie back (7)
I believe the answer is:
recline
'lie back' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for recline that I've seen before include "Lie on the back or side" , "Lie back and take it easy" , "Adopt horizontal or leaning position" , "Lie in a comfortable position" , "Lounge" .)