Treat hide by beating? (3)

I believe the answer is:

tan

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

'treat hide' is the definition.
(I've seen this in another clue)

I don't understand the remainder of the clue.

(Other definitions for tan that I've seen before include "Yellowish brown" , "Sun-baked colour" , "Turn dark in sun" , "Brown colour acquired from sun" , "Make black and blue" .)

I've seen this clue in the Evening Standard.

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