Compulsive clenching of fists? (8)

I believe the answer is:
gripping
'compulsive' is the definition.
(thesaurus)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for gripping that I've seen before include "Holding tightly" , "Enthralling" , "Sensational" , "Suspenseful" , "Grasping" .)
