Crossword Genius

One will cut down oak, say, upset thanks to abuse (3-5)

Ross

I believe the answer is:

ill-treat

But I can't explain it at all!

(Other definitions for ill-treat that I've seen before include "Act cruelly towards (someone)" , "Misuse" , "Use someone badly or cruelly" , "Subject to cruel or abusive usage" , "Abuse" .)

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