Told off by fool (4)
I believe the answer is:
dolt
'fool' is the definition.
(I know that fool can be written as dolt)
'told off' is the wordplay.
'off' indicates an anagram.
'told' is an anagram of 'DOLT'.
'by' acts as a link.
(Other definitions for dolt that I've seen before include "Dullard" , "Slow-witted type" , "Idiot" , "Dimwit" , "Halfwit" .)