### Clue: Force loosened Ron's extremely strong grip (7)
### Answer: ENGROSS 
 ### Explanation: Definition: grip
 E(or, strictly, the lower-case Greek "Epsilon" written large, symbol for "electromotive force" in physics, not to be confused with E for "energy") + **anagram of**(loosened) [RON'S + **1st and last letters of**(extremely) "strong"].
Defn: …/to hold one's attention or interest.