An order that can madden? (6)
I believe the answer is:
demand
'an order' is the definition.
(thesaurus)
'can madden?' is the wordplay.
'can' indicates anagramming the letters (I've seen 'canned' mean this (canned can mean drunk)).
'madden' with letters rearranged gives 'DEMAND'.
'that' acts as a link.
(Other definitions for demand that I've seen before include "Require, need" , "Ask - what the public wants" , "Insistent request" , "Request urgently" , "Request forcefully" .)