Say otherwise in regard to yokel (7)
I believe the answer is:
hayseed
'to yokel' is the definition.
(synonyms)
'say otherwise in regard' is the wordplay.
'otherwise' indicates an anagram.
'in' is an insertion indicator.
'regard' becomes 'heed' (synonyms).
'say' is an anagram of 'ays'.
'ays' put into 'heed' is 'HAYSEED'.
(Other definitions for hayseed that I've seen before include "Yokel" , "Countryman" , "Simple country person" , "Rustic" , "Had eyes (anag.)" .)