Answer:

subset

Answer	Crossword Clue
SUBSET	Part of a larger group
SUBSET	Squares, vis- -vis quadrilaterals
SUBSET	Group within a group

SUBSET	Squares, vis-a-vis quadrilaterals
SUBSET	Included group
SUBSET	Minks, to weasels
SUBSET	Conifers, to trees
SUBSET	Venn diagram representation
SUBSET	Beetles, vis- -vis insects
SUBSET	Group in a group
SUBSET	Reduced number

SUBSET	Math group within a group
SUBSET	Men, vis-a-vis human beings
SUBSET	Lower class?
SUBSET	Inner circle in a Venn diagram
SUBSET	Circle within a circle, in a Venn diagram