Trying to work the clue rather than the answer.
Down clue
Shun this short notice (9).
A T T E N T I O N fits the answer.
ATTENTION as a notice.
Where does SHUN come in? The sound of ATTENSHUN? What about the rest? AT TEN. Is that supposed to indicate short notice e.g. at ten (o'clock)? Or am I barking up the wrong tree altogether and not seeing the obvious?!!