mitt vs clenched fist

mitt and clenched fist both are nouns.

Word	Noun	Adjective	Verb	Adverb
mitt	Yes	No	No	No
clenched fist	Yes	No	No	No

As nouns, clenched fist is a hyponym of mitt; that is, clenched fist is a word with a more specific, narrower meaning than mitt:

mitt: the (prehensile) extremity of the superior limb
clenched fist: a hand with the fingers clenched in the palm (as for hitting)

Other hyponyms of mitt include fist, hooks, maulers, meat hooks, right, right hand, left, left hand.

mitt (noun)	clenched fist (noun)
the handwear used by fielders in playing baseball	a hand with the fingers clenched in the palm (as for hitting)
the (prehensile) extremity of the superior limb