Pain from stomach eases (4)
I believe the answer is:
ache
'pain' is the definition.
(ache is a kind of pain)
'from stomach eases' is the wordplay.
'from' indicates the answer is hidden within the clue.
'ACHE' is hidden in the letters of 'stomach eases'.
(Other definitions for ache that I've seen before include "strong feeling" , "Continuous hurt" , "Hanker" , "yearning" , "Take an aspirin for it" .)