Pain; yearn (4)
I believe the answer is:
ache
This clue is a double definition.
'pain' is the first definition.
(ache is a kind of pain)
'yearn' is the second definition.
(synonyms)
(Other definitions for ache that I've seen before include "Nagging pain" , "Throb - hurt" , "Cause pain" , "Persistent dull pain" , "Shakespearean character" .)