Rustic couple left (5)
I believe the answer is:
yokel
'rustic' is the definition.
(yokel is a kind of rustic)
'couple left' is the wordplay.
'couple' becomes 'yoke' ('yoke' can be a synonym of 'couple'**).
'left' becomes 'l' (common abbreviation).
'yoke'+'l'='YOKEL'
(Other definitions for yokel that I've seen before include "Bumpkin - rustic" , "Country bumpkin" , "Simple rustic" , "Unsophisticated country person" , "rustic type" .)