Answer:

SAND

Answer	Crossword Clue
SAND	Castle material?
SAND	Make smooth
SAND	Smooth down

SAND	... box: playground feature
SAND	Bunker filler
SAND	Chopin's companion
SAND	Starter for bar or bag
SAND	Word before hill or dollar
SAND	Beach covering
SAND	Hourglass contents
SAND	1966 Steve McQueen film, "The ... Castles"

SAND	Construction material for some castles
SAND	1989 R.E.M. single
SAND	Grit in a golf trap
SAND	Hourglass material
SAND	Work on wood
SAND	Chopin companion
SAND	Hourglass filler
SAND	Analog for time

SAND	Castle composition
SAND	Smooth wood
SAND	Bunker stuff
SAND	Bank deposit?
SAND	Castle-building material
SAND	Neutral hue
SAND	Take the edge off?
SAND	Hourglass fill

SAND	"The Devil's Pool" novelist
SAND	Beach blanket?
SAND	Shore thing
SAND	Box filler
SAND	Dune makeup
SAND	Castle material, perhaps
SAND	Beach, mostly
SAND	Beach surface

SAND	Beachfront property?
SAND	Between-your-toes grains
SAND	Hourglass flow
SAND	Smooth in the shop
SAND	Golf hazard, often