A batty sort of tree? (6)

I believe the answer is:

willow

I'm a little stuck... Click here to teach me more about this clue!

'tree?' is the definition.
(I know that willow is a type of tree)

I cannot understand how the rest of the clue works.

(Other definitions for willow that I've seen before include "Quick-growing tree with flexible branches" , "Waterside tree" , "Pussy- - -" , "Tree of the salix family" , "Sally tree" .)

I've seen this clue in the Evening Standard.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.