Be too hot, as water (4)

I believe the answer is:

burn

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

'water' is the definition.

I can't explain the rest of the clue.

(Other definitions for burn that I've seen before include "Go up in flames; stream" , "northern stream" , "Set 1 across [ALIGHT]" , "Incinerate" , "Heat injury; stream" .)

I've seen this clue in the Evening Standard.

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