Black bats (these ones?) (8)
I believe the answer is:
brackets
'these ones?' is the definition.
The definition suggests an adverb but the answer is not.
'black bats' is the wordplay.
'black' becomes 'b' (abbreviation as in pencil classifications).
'bats' becomes 'rackets' (I've seen this before).
'b'+'rackets'='BRACKETS'
Can you help me to learn more?
(Other definitions for brackets that I've seen before include "eight here in these" , "Projecting supports, for a shelf say" .)