Answer:

kneecap

Answer	Crossword Clue
KNEECAP	Patella
KNEECAP	Leg joint protector
KNEECAP	Bump on a leg

KNEECAP	Triangular leg bone
KNEECAP	Plate above a certain strike zone
KNEECAP	Football pad beneficiary
KNEECAP	Shinbone neighbor
KNEECAP	A pad may protect it
KNEECAP	Flat bone
KNEECAP	Gangster's target, maybe
KNEECAP	Start of the strike zone

KNEECAP	What a mob goon threatens to break
KNEECAP	Prayer foundation?
KNEECAP	Joint protector
KNEECAP	Largest sesamoid bone in the body