A sore possibly appeared (5)
I believe the answer is:
arose
'appeared' is the definition.
(I've seen this before)
'a sore possibly' is the wordplay.
'possibly' indicates an anagram.
'sore' with letters rearranged gives 'rose'.
'a'+'rose'='AROSE'
(Other definitions for arose that I've seen before include "appeared" , "''. ... by any other name would smell as sweet'' (Romeo and Juliet)" , "Issued" , "stemmed" , "Became apparent" .)