In fury, a member's run amok (7)
I believe the answer is:
rampage
'run amok' is the definition.
(thesaurus)
'in fury a member's' is the wordplay.
'in' indicates putting letters inside.
'fury' becomes 'rage' ('rage' can be a synonym of 'fury').
'member' becomes 'mp'.
'a'+'mp'='amp'
'rage' placed around 'amp' is 'RAMPAGE'.
(Other definitions for rampage that I've seen before include "Rioting, for example" , "Map gear (anag.)" , "A mad rush" , "Run wild" , "destructive behaviour" .)