Pain bachelor's hiding (4)
I believe the answer is:
ache
'pain' is the definition.
(ache is a kind of pain)
'bachelor's hiding' is the wordplay.
'hiding' indicates the answer is hidden within the clue.
'ACHE' is hidden in the letters of 'bachelors'.
(Other definitions for ache that I've seen before include "Persistent dull pain" , "Hurt; yearn" , "Similar" , "Shakespearean character" , "Throb - hurt" .)