Going through each year is painful (4)
I believe the answer is:
achy
'painful' is the definition.
(similar in meaning)
'going through each year is' is the wordplay.
'going through' says the answer is hidden in the clue.
'ACHY' can be found hidden inside 'each year is'.
(Other definitions for achy that I've seen before include "suffering dull pain" , "Suffering minor pains" , "Persistently painful" , "Pained expression" , "Continuously painful" .)