Badmouth country gent on a regular basis (6)
I believe the answer is:
malign
'badmouth' is the definition.
(synonyms)
'country gent on a regular basis' is the wordplay.
'country' becomes 'mali' (Mali is an example).
'on a regular basis' means one should take alternating letters.
The alternating letters of 'gent' are 'gn'.
'mali'+'gn'='MALIGN'
(Other definitions for malign that I've seen before include "Evil-natured" , "Of ill intent" , "Say unpleasant and untrue things about" , "Laming, showing malice" , "Evil in nature" .)