Black rabbit in bush (7)
I believe the answer is:
bramble
'in bush' is the definition.
'bramble' can be an answer for 'bush' (thesaurus). I am not sure about the 'in' bit.
'black rabbit' is the wordplay.
I cannot quite see how this works, but
'black' could be 'b' (as in pencil classifications) and 'b' is found in the answer.
The remaining letters 'ramble' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for bramble that I've seen before include "Blackberry plant" , "Gather fruit" , "Prickly hazard" , "Prickly plant yielding blackberries" , "Rough, prickly shrub" .)