I get the diamond bit, but what's the rest of the clue about?
I'm sure Usain Bolt is a anagram of something interesting too, but I can't remember what.
My favourite Grauniad clue was by the great Araucaria, one of my ultimate heroes - on a par with Mingus, Peter Walker and Robertson Davies. I urge you to read his Wikipedia entry if you don't know about him. Anyway, the clue is 'Cox at me (6,3,6)'.
Warning - if you Google it you get the answer.
You remember all sorts of weird things from doing crosswords for a while. Like Manchester City is an anagram of synthetic cream.
I always get the impression that the setter is sitting there with a sardonic smile and a superior air as if to say "Yes...I am actually extremely clever, and, well, I can see that you really haven't grasped this, have you?"