The part a rabbit can't be without (3)
I believe the answer is:
bit
'be without' is the definition.
I can't tell whether this definition defines the answer.
'the part a rabbit can't' is the wordplay.
'the part' says the answer is hidden in the clue.
'BIT' can be found hidden inside 'rabbit cant'.
Can you help me to learn more?
(Other definitions for bit that I've seen before include "Mouthpiece of brindle or tip of drilling tool" , "Small fragment" , "Data measurement unit" , "Unit of information" , "Sank teeth in" .)