Force cutting signal, energy maintained (5)
I believe the answer is:
impel
'force' is the definition.
(synonyms)
'cutting signal energy maintained' is the wordplay.
'cutting' means to remove the last letter.
'signal' becomes 'imply'.
'energy' becomes 'e' (physics symbol as in E=mc2).
'maintained' indicates putting letters inside (inserted letters get controlled or maintained).
'imply' with its last letter taken away is 'impl'.
'impl' going around 'e' is 'IMPEL'.
(Other definitions for impel that I've seen before include "Cause to move forward" , "Motivate" , "Force forwards" , "Oblige" , "Make" .)