Gorge, mostly mad with energy (6)
I believe the answer is:
ravine
'gorge' is the definition.
(I know that gorge can be written as ravine)
'mostly mad with energy' is the wordplay.
I cannot really see how this works, but
'energy' could be 'e' (physics symbol as in E=mc2) and 'e' is found within the answer.
The remaining letters 'ravin' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for ravine that I've seen before include "Type of gorge" , "Canyon" , "Defile" , "Deep narrow gorge between mountains" , "'Deep, steep valley (6)'" .)