Clue: Action blamed for embarrassingly affected manner, as boob revealed on the catwalk? (8,11)
Answer: WARDROBE MALFUNCTION
Explanation: Definition: boob revealed on the catwalk
I can't quite parse this – it's an anagram of ACTION BLAMED FOR + WRUN, but I cant account for the extra four letters. The expression, for the "accidental" revealing of naughty bits, is said to have originated from this incident.
 *Thanks to morphiamet – it's WAR (action) + (BLAMED FOR)* + UNCTION.