Pain in each ear (4)
I believe the answer is:
ache
'pain' is the definition.
(ache is a kind of pain)
'in each ear' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ACHE' is hidden within 'each ear'.
(Other definitions for ache that I've seen before include "Take an aspirin for it" , "Pine" , "Shakespearean character" , "Feel sore" , "Dull continuous pain" .)