Scalding does it no harm (3)
I believe the answer is:
tea
'no harm' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'scalding does it' is the wordplay.
I cannot quite see how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is present in the answer.
The remaining letters 'ea' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for tea that I've seen before include "Light afternoon repast" , "Brew" , "and 18 Across: Utensils for afternoon meal" , "Lapsang souchong" , "Darjeeling, e.g." .)