To take or try to take hold of something tightly, usually in fear, worry. or pain. (Cambridge Dictionary)
If you clutch at something or clutch something, you hold it tightly, usually because you are afraid or anxious. (Collins Dictionary)
Grasp (something) tightly. (Oxford Dictionaries)
To grasp or hold with or as if with the hand or claws usually strongly, tightly, or suddenly. (Merriam – Webster)
Definition of clutch. – Engineering Dictionary.
Clutch definition. The Free Dictionary.