Bring up Republican auditor behind back (4)
I believe the answer is:
rear
I believe this clue is a quadruple definition!!
'bring' is the first definition.
(thesaurus)
'up' is the second definition.
(thesaurus)
'republican auditor behind' is the third definition.
'rear' can be an answer for 'behind' (synonyms). I'm unsure of the 'republican auditor' bit.
'back' is the fourth definition.
(synonyms)
(Other definitions for rear that I've seen before include "Buttocks - rise up" , "Back; bring up (young)" , "Foster" , "The back part of something" , "Jump" .)