Dull persistent pains (5)
I believe the answer is:
aches
'dull persistent pains' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for aches that I've seen before include "Hurts; yearns" , "Gives a dull pain" , "Dull persistent pains" , "Dull prolonged pains" , "Constant pains" .)