17 across
Small
untruth
by
rector
is
more
cunning
(5)
Small untruth by rector is more cunning (5)
hints
0
checks
0
hints
The definition is at the end of the clue.
How the clue works
Look at more cunning — that's your definition. Then it's just a matter of building the word piece by piece: S for small, followed by LIE (an untruth), and finally R for rector.