Mr Stickers, who will be prosecuted, one notices? (4)
I believe the answer is:
bill
'mr' is the definition.
(short for William)
'stickers who will be prosecuted one notices?' is the wordplay.
I cannot really see how this works, but
'will' could be 'll' (contracted form, as in 'he'll' - 'he will') and 'll' is located in the answer.
'one' could be 'i' (Roman numeral) and 'i' is found in the answer.
A single letter 'b' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for bill that I've seen before include "Circular - account" , "Poster; draft law" , "Invoice; man's name" , "Invoice; beak" , "List of charges" .)