Force loosened Ron's extremely strong grip (7)
I believe the answer is:
engross
'grip' is the definition.
(thesaurus)
'force loosened ron's extremely strong' is the wordplay.
'force' becomes 'e' (E is the symbol of electromotive force).
'loosened' indicates anagramming the letters.
'extremely' says to hollow out the word (remove centre letters).
'strong' with its middle taken out is 'sg'.
'rons'+'sg'='ronssg'
'ronssg' anagrammed gives 'ngross'.
'e'+'ngross'='ENGROSS'
(Other definitions for engross that I've seen before include "Rivet" , "Completely absorb" , "Engulf" , "Totally absorb the attention of" , "Occupy attention fully, absorb" .)