The phrase 'witty idea' is correct and usable in written English.
You could use it to describe a clever idea or solution. For example, "Her witty idea of using the bicycle to power the light show was a huge success."
Who thought that having William Shatner review MacFarlane's performance from the future was a witty idea?
It's certainly a witty idea to posh the Twits up as a pair of disgusting toffs.
It's a wonderfully witty idea, but it's both too big and too small.
A few years ago, The Guardian had the witty idea to ask its sports writers and cultural critics to swap jobs for a day.
The creators come up with a goofy or witty idea, put it up on a simple platform like Twitter and Tumblr, and wait for contributors to provide all of the content.
Quetsch, a posh plum, made a delicious tart and came with an ice-cream made out of its pit – a lovely, witty idea, but the ice-cream's faintly almond-like flavour was so subtle, you had to concentrate hard to detect it.
It was a clever - and witty - idea to dig up Donizetti's little-known early opera Emilia di Liverpool and entrust it to the locally based touring group Opera Europe; so why hide it away before the opening weekend?
Critics have not been so kind to Skin Deep, an operetta about cosmetic surgery for which Iannucci wrote the lyrics, now on in Leeds; but as always his words are witty, the idea is ingenious, and the satire is on the mark.
Mr. Whitehouse's small, witty visual ideas are always more incisive than his larger thinking.
Firstly there are Meller's witty visual ideas, with their Freudian allusions and flirtations with the unconscious.
There is nothing particularly new or witty about the idea of wax objects that are shaped like edibles — as early as 1964, my brother bit into a wax apple that my Aunt Helen had in a bowl on her sideboard — and yet that may be exactly why a throwback like me was attracted to the pear candles.
