Possible Clues:

• Muscle and tissue at the back of the roof of the mouth
• Uvula's location (In this answer, note the first letter + the last 4)
• Frequently found in spring, dead tissue in mouth
• Dim friend put away oral part
• Mouthy type is not hard on what 13 down have
• Muscular flap used in swallowing or speaking
• Rear of the roof of the mouth