Pub bum tends not to disclose slur (8)
I believe the answer is:
innuendo
'slur' is the definition.
(I've seen this before)
'pub bum tends not to disclose' is the wordplay.
I cannot really understand how this works, but
'pub' could be 'inn' (an inn is a type of pub) and 'inn' is found within the answer.
'not' could be 'o' (I've seen this in other clues) and 'o' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for innuendo that I've seen before include "Insinuation, implication" , "Indirect reference to something rude" , "Naughty suggestion" , "derogatory reference" , "Subtle disparagement" .)