Nagging feeling (3)
I believe the answer is:
yen
'nagging feeling' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for yen that I've seen before include "Long for Japanese money?" , "Currency of Japan" , "Intense desire for a Japanese coin" , "Itch, craving" , "Japanese unit of money" .)