A source of pain in past years (4)
I believe the answer is:
stye
'a source of pain' is the definition.
I can't tell whether this defines the answer.
'in past years' is the wordplay.
'in' indicates the answer is hidden within the clue.
'STYE' is hidden in the letters of 'past years'.
Can you help me to learn more?
(Other definitions for stye that I've seen before include "producing eyesore" , "Tamworth residence" , "Inflammation around the eye" , "Eye problem" , "Seeing problem" .)