Develop sores (8)
I believe the answer is:
ulcerate
'develop sores' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ulcerate that I've seen before include "Become affected by open sores -- late cure (anag)" , "Become inflamed and infected" , "Form open sore" , "Erupt into sores" .)