15 across
Hoax
has
taken
in
famous
10
(7)
Hoax has taken in famous 10 (7)
hints
0
checks
0
hints
The definition is at the end of the clue.
How the clue works
The definition is 10, which cross-references 10 across (FOOL) — Costard being a foolish character in Love's Labour's Lost. The wordplay uses a container: COD (meaning "hoax") wraps around STAR (meaning "famous"), indicated by "has taken in". That gives CO-STAR-D, spelling COSTARD.