4 down
Duck
under
perfect
child
in
martial
art
(6)
Duck under perfect child in martial art (6)
hints
0
checks
0
hints
The definition is at the end of the clue.
How the clue works
Look at martial art at the end — that's what you're after. The wordplay builds it up piece by piece: AI meaning first-class or "perfect", followed by KID for "child", then O for "duck" (a zero score in cricket).