Crossword Genius

Mark, showing stress, runs away (5)

Ross

I believe the answer is:

stain

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

'mark' is the definition.
(I know that mark can be written as stain)

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

Can you help me to learn more?

(Other definitions for stain that I've seen before include "Black mark for saint" , "Smear" , "Satin (anag.)" , "Discolouration" , "Stigma" .)

I've seen this clue in The Sun.
Want a hint initially instead of a full solution? Install my app