Official with power to prohibit distribution of material (6)
I believe the answer is:
censor
'official with power to prohibit distribution of material' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for censor that I've seen before include "One vetting films, etc" , "Wielder of blue pencil" , "Remove offensive parts" , "Forbid public distribution" , "Wield a blue pencil" .)