Grabs wife and relaxes (6)
I believe the answer is:
wrests
'grabs' is the definition.
('wrest' can be a synonym of 'grab')
'wife and relaxes' is the wordplay.
'wife' becomes 'w' (abbreviation).
'and' says to put letters next to each other.
'relaxes' becomes 'rests' (I've seen this before).
'w'+'rests'='WRESTS'
(Other definitions for wrests that I've seen before include "Seizes forcibly" , "Takes" , "Obtain by seizing forcibly or violently" .)