Not providing firm foothold: like moccasin? (8)

I believe the answer is:

slippery

I believe this is a double definition.

'not providing firm foothold' is the first definition.
(something slippery has no firm footing)

'like moccasin?' is the second definition.
(a moccasin is a type of slipper)

(Other definitions for slippery that I've seen before include "Unreliable" , "Evasive, elusive" , "Not to be trusted" , "Evasive like an eel" , "Hard to grasp, like an eel" .)

I've seen this clue in The Sun.

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