Salacious material turning stomachs (4)
I believe the answer is:
smut
'salacious material' is the definition.
(I've seen this in another clue)
'turning stomachs' is the wordplay.
'turning' shows that the letters should be reversed in order.
'stomachs' becomes 'tums' ('tum' can be a synonym of 'stomach').
'tums' reversed gives 'SMUT'.
(Other definitions for smut that I've seen before include "Obscene word(s)" , "Obscene talk" , "Pornography or grime" , "Flake of soot or dirt" , "Soot flake or sexual innuendo" .)