Speak harshly, maybe heatedly (5)
I believe the answer is:
grate
'speak' is the definition.
Although both the answer and definition are verbs in their base form, I cannot see how they can define each other.
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for grate that I've seen before include "Grind, rasp" , "Reduce to small shreds" , "Grind (cheese)" , "Grind (teeth)" , "irritating" .)