Relax, say, occasionally relaxed (4)
I believe the answer is:
easy
'relaxed' is the definition.
(associated in meaning)
'relax say occasionally' is the wordplay.
'occasionally' means one should take alternating letters (letters taken at regular intervals or occasions).
'relax'+'say'='relaxsay'
The alternating letters of 'relaxsay' are 'EASY'.
(Other definitions for easy that I've seen before include "Convenient" , "Child's play" , "Posing no difficulty" , "Requiring little effort" , "for a piece of cake" .)