Restriction gets Bruce no end upset! (4)
I believe the answer is:
curb
'restriction' is the definition.
(thesaurus)
'bruce no end upset' is the wordplay.
'no end' means to remove the last letter.
'upset' says the letters should be written backwards.
'bruce' with its final letter removed is 'bruc'.
'bruc' reversed gives 'CURB'.
'gets' is the link.
(Other definitions for curb that I've seen before include "Muzzle" , "Restrain, perhaps your enthusiasm" , "'Temper, hold in restraint (4)'" , "Strap used to restrain horse" , "Restrain, inhibit" .)