Clue: Vague old American with scholar up at famous university (9)
Answer: AMBIGUOUS
Explanation: Vague old American with scholar up at famous university (9)
**O** (old) + **US** ("American") *with* **<=M.A.** ("scholar", *up*) *at* **BIG** ("famous") **U** (university), so **A.M.-BIG-U-O-US