Being a bit of a dog, is crooked (3)
I believe the answer is:
leg
'being' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for leg that I've seen before include "Lower limb" , "Projecting support for chair or table" , "prop" , "Section of journey; limb" , "Member" .)