SPARE a thought for crazy caricaturist and manic magician Bill Yim who has a Gieves & Hawkes gift certificate worth $2,000, which he does not know how to dispose of. This venerated shop, which has been supplying the clothing needs of bankers, bishops and retired majors and brigadiers for decades, is not the type of place one would expect to see Bill - whose dress sense could best be described as neo-scruffy (he was afashion victim of grunge before the word entered the haute couture dictionary). He was given the gift certificate after winning a ''Best Braces in Hongkong'' contest at which CNN's Larry King was adjudicator - although Bill said the reason his personally designed braces were festooned with pictures of semi-clad ladies in suspenders was because braces were referred to as suspenders in the US. ''The way I dress, I'm not too sure whether I'd be allowed into the Gieves & Hawkes shop in Central,'' said Bill. ''Anyway, I've been told there's not a lot I can get there for $2,000. Maybe I could use the gift certificate to put down a deposit on a pair of braces.''