Answer:

sub

Answer	Crossword Clue
SUB	Deli offering
SUB	Temp. teacher
SUB	Deli order, sometimes

SUB	Hero
SUB	Bench-warmer
SUB	Grinder's kin
SUB	Stand-in
SUB	"Nautilus," for one
SUB	Second-stringer
SUB	Long lunch?
SUB	Player off the pine

SUB	Lunch on a roll
SUB	The USS Jimmy Carter, e.g.
SUB	Teacher for a day
SUB	Temporary teacher
SUB	Player filler in
SUB	Long sandwich
SUB	Nautilus, e.g.
SUB	One may be needed after an injury

SUB	Underwater vessel
SUB	Benchwarmer
SUB	U-boat, e.g.
SUB	Deli choice
SUB	Hefty sandwich
SUB	Torpedo, or its launcher
SUB	Ocean traveler
SUB	Red October, for one

SUB	Sizable sandwich
SUB	Pinch hitter
SUB	Sonar user
SUB	The Nautilus, for one
SUB	Stand in
SUB	Temp
SUB	Long lunch, for short
SUB	Large sandwich, for short

SUB	Come off the bench (for)
SUB	Lead-in for zero or prime
SUB	Diving craft
SUB	One may be needed after a sports injury
SUB	Undersea prowler