A painful affliction regularly hits rodents (7)
I believe the answer is:
agoutis
'rodents' is the definition.
(I've seen this before)
'a painful affliction regularly hits' is the wordplay.
'painful affliction' becomes 'gout'.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
The alternate letters of 'hits' are 'is'.
'a'+'gout'+'is'='AGOUTIS'
(Other definitions for agoutis that I've seen before include "More than one animal" , "Rodents" .)