Censor's target (4)
I believe the answer is:
smut
'censor's target' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for smut that I've seen before include "Soot flake or sexual innuendo" , "black spot" , "Pornography or grime" , "Sooty matter" , "Small soot flake or indecent talk" .)