Conviction for injecting double energy into high explosive (5)
I believe the answer is:
tenet
'conviction' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for tenet that I've seen before include "Key principle" , "Canon" , "Palindromic principle or belief" , "A palindromic doctrine or creed" , "Doctrine held to be true" .)