Answer:

core

Answer	Crossword Clue
CORE	Part of a reactor
CORE	Word before curriculum or meltdown
CORE	Apple throwaway

CORE	Uneaten part of an apple
CORE	Common ...
CORE	Heart
CORE	Middle Earth?
CORE	Muscle group targeted by Pilates
CORE	... curriculum
CORE	Mandatory courses
CORE	Abs and such

CORE	Fitness center?
CORE	Geological sample
CORE	Compulsory courses
CORE	Center
CORE	Essence
CORE	Part of a planet
CORE	Kind of curriculum
CORE	Nuclear reactor part

CORE	Part of the earth
CORE	Part of an apple or the earth
CORE	Part of an apple
CORE	Where a pear's seeds are
CORE	Apple seeds' location
CORE	Curriculum part
CORE	Set of classes all students must take
CORE	Very center

CORE	Pith
CORE	Middle earth?
CORE	Nub
CORE	Apple leftover
CORE	Delicious leftover
CORE	Rights org.
CORE	Like some college curricula
CORE	Heart of a Baldwin

CORE	Place for seeds
CORE	Apple seeds' site
CORE	Rotten to the ...
CORE	Like some beliefs
CORE	Reactor part