One with energy boxing foremost of Romany's Fury (3)
I believe the answer is:
ire
'fury' is the definition.
(I've seen this before)
'one with energy boxing foremost of romany's' is the wordplay.
'one' becomes 'i' (Roman numeral**).
'with' says to put letters next to each other.
'energy' becomes 'e' (physics symbol as in E=mc2).
'boxing' indicates putting letters inside ('box' can mean contain, as in to put in a box).
'foremost of' indicates taking the first letters.
The first letter of 'romanys' is 'r'.
'i'+'e'='ie'
'ie' placed around 'r' is 'IRE'.
(Other definitions for ire that I've seen before include "Irritation, anger" , "Strong feeling" , "Annoyance, vexation" , "Displeasure" , "passion" .)