Trim redcoat going around with energy (8)
I believe the answer is:
decorate
'trim' is the definition.
(I've seen this in another clue)
'redcoat going around with energy' is the wordplay.
'going around with' is an anagram indicator.
'energy' becomes 'e' (physics symbol as in E=mc2).
'redcoat' anagrammed with 'e' makes 'DECORATE'.
(Other definitions for decorate that I've seen before include "'Adorn, embellish (8)'" , "Add ornamentation to" , "Improve the look of" , "Honour" , "'Adorn, beautify (8)'" .)