Vicious criminal beheaded revenue collector round back of office (6)
I believe the answer is:
axeman
'vicious criminal' is the definition.
(someone wielding an axe)
'beheaded revenue collector round back of office' is the wordplay.
'beheaded' means to remove the first letter (the head of the word is removed).
'revenue collector' becomes 'taxman' (collector of tax revenues).
'round' indicates putting letters inside.
'back of' says to take the final letters.
The last letter of 'office' is 'e'.
'taxman' with its first letter taken off is 'axman'.
'axman' going around 'e' is 'AXEMAN'.
(Other definitions for axeman that I've seen before include "Guitarist (slang)" , "Killer" , "One wielding chopper" , "Tree feller - executioner" , "One using a chopper" .)