South American native that’s on slippery slope (5)
I believe the answer is:
scree
'that's on slippery slope' is the definition.
(rocks on a mountain slope)
'south american native' is the wordplay.
'south' becomes 'S' (abbreviation).
'american native' becomes 'cree' (Native American).
's'+'cree'='SCREE'
(Other definitions for scree that I've seen before include "Sloping mass of rocks at the base of a cliff" , "Loose stones around a mountain" , "Rock debris at the base of a cliff" , "Steep, stony slope" , "Loose debris on a mountain slope" .)