High on the Scoville scale (3)
I believe the answer is:
hot
'high on the scoville scale' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for hot that I've seen before include "Intense - illegal - dangerous" , "Torrid" , "Very popular" , "recently stolen" , "(Of food) spicy" .)