Burden left for rustic (5)
I believe the answer is:
yokel
'rustic' is the definition.
(yokel is a kind of rustic)
'burden left' is the wordplay.
'burden' becomes 'yoke' (I've seen this before).
'left' becomes 'l' (common abbreviation).
'yoke'+'l'='YOKEL'
'for' is the link.
(Other definitions for yokel that I've seen before include "Unsophisticated country person" , "Hick" , "Countryman" , "Hayseed" , "Rustic person (derogatory)" .)