Take a knock (3)
I believe the answer is:
bat
This might be a double definition.
'take' is the first definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'a knock' is the second definition.
(thesaurus)
Can you help me to learn more?
(Other definitions for bat that I've seen before include "Nocturnal flier" , "Night flier" , "Creature" , "Small flying mammal - like 11 Across" , "Nocturnal animal - racket" .)