Queen energy new in record soon (7)
I believe the answer is:
erelong
'soon' is the definition.
(archaic word meaning 'soon')
'queen energy new in record' is the wordplay.
'queen' becomes 'ER' (short for Elizabeth Regina ie Queen Elizabeth).
'energy' becomes 'e' (physics symbol as in E=mc2).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'in' indicates putting letters inside.
'record' becomes 'log' (log is a kind of record).
'n' going inside 'log' is 'long'.
'er'+'e'+'long'='ERELONG'
(Other definitions for erelong that I've seen before include "Soon (poetically)" , "Soon (archaic)" , "Soon (arch.)" , "Soon (poetic)" .)