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Thanks, cruciverbali, that's confirmed a couple of my thoughts but, alas, completely confused one other!
23d cannot be an anagram of Lead is a new as that is two letters too many; also, unless I have gone completely wrong elsewhere, it should end in B..... making the answer Spin a Web.
Do you concur?
Hang on - just had a blinding flash of light: use the chemical symbol rather than the metal and the anagram leaps out...
Thanks, cruciverbali, for kick-starting my brain.