Stop being loyal (7)
I believe the answer is:
staunch
I believe this is a double definition.
'stop' is the first definition.
(I know that staunch is a more specific form of the action check)
'loyal' is the second definition.
(I've seen this in another clue)
'being' is the link.
(Other definitions for staunch that I've seen before include "Trusty - steadfast" , "Stop bleeding; trusty" , "Hun acts in firm and loyal way" , "Plug" , "Sturdy" .)