Related Clues:

• Grassy square
• Astrodome field's lack
• Replacement grass, perhaps
• Putting green patch
• Clump of turf
• Lawn component
• Sward
• 19-Across (with "Old")
• Square with roots
• Green topper
• Landscaper's cover
• Layer of ground
• Plot thickener
• Fairway makeup
• Course material, maybe