Laid-back (6)
I believe the answer is:
mellow
'laid-back' is the definition.
(I know that laid-back can be written as mellow)
This is all the clue.
(Other definitions for mellow that I've seen before include "under the influence of drink" , "Relaxed, good-humoured" , "Soft, cheerful, relaxed" , "Calm and relaxed" , "Relaxed and mature" .)