A hand with the fingers clenched or curled inward.
“The boxer's fists rained down on his opponent in the last round.”
The characteristic signaling rhythm of an individual telegraph or CW operator when sending Morse code.
verb
To strike with the fist.
“...may not score a point with his open hand(s), but may score a point by fisting the ball. Damian Cullen. "Running the rule." The Irish Times 18 Aug 2003, pg. 52.”