Stop putting energy in container (5)
I believe the answer is:
cease
'stop' is the definition.
(synonyms)
'putting energy in container' is the wordplay.
'putting energy' becomes 'e' (I can't explain this - if you can you should believe this answer much more).
'in' is an insertion indicator.
'container' becomes 'case' (case is a kind of container).
'e' inserted within 'case' is 'CEASE'.
Can you help me to learn more?
(Other definitions for cease that I've seen before include "Culminate" , "Stop, finish" , "Come to an end" , "Finish, end" , "Political group" .)