X of snot repelled turn-out (4)
I believe the answer is:
scum
'x of snot' is the definition.
'scum' can be an answer for 'snot' (thesaurus). I am not sure about the 'x of' bit.
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for scum that I've seen before include "Floating impurities or worthless people" , "Floating impurities on liquid" , "The lowest" , "Algae" , "Floating impurities or bad people" .)