Animal easily crossed with a dog (5)

I believe the answer is:

zebra

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

'animal' is the definition.
(I've seen this before)

I don't understand how the rest of the clue works.

(Other definitions for zebra that I've seen before include "Stripy member of horse family" , "that's stripy" , "African species" , "Kind of crossing?" , "Striped mammal" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app