Possible Clues:

• What 25 across has and what 23 across might have
• Cover in the woods
• Give tongue arouond the tree
• Lab output?
• Dogwood cover, aptly
• Characteristic of a dog to obstruct kennel's opening
• Bay -- covered by this?
• Outermost tree layer
• Former president familiarly ignoring bill for sailing ship
• Part of a tree