Assistants caging black bears (6)
I believe the answer is:
abides
'bears' is the definition.
('abide' can be a synonym of 'bear')
'assistants caging black' is the wordplay.
'assistants' becomes 'aides' (aide is a kind of assistant).
'caging' means one lot of letters goes inside another (I've seen this in other clues).
'black' becomes 'b' (as in pencil classifications).
'aides' going around 'b' is 'ABIDES'.
(Other definitions for abides that I've seen before include "Dwells (archaic)" , "Continues without fading or being lost, memory perhaps" , "Lives or tolerates" , "Acts in accordance with rules" , "Stays" .)