Remainder; relax (4)
I believe the answer is:
rest
I believe this is a double definition.
'remainder' is the first definition.
(I know that remainder can be written as rest)
'relax' is the second definition.
(to relax is to have a rest)
(Other definitions for rest that I've seen before include "Change is as good as this, they say" , "Calm" , "Remainder; cease work" , "Others; relax" , "Relax with residue" .)