clenched fist vs mitt

clenched fist and mitt both are nouns.

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

As nouns, mitt is a hypernym of clenched fist; that is, mitt is a word with a broader meaning than clenched fist:

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

Other hypernyms of clenched fist include hand, manus, paw.

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