AJT - the word you are looking for is a proper name similar to 22a (8 letters), another scale.
Google all the unclued lights and that should lead you to it. If not I'm staying at my computer now for the next hour so I'll watch the site.
Right, that's it, apart from 39a - is this a synonym for 'weak'? Rather puzzled by the wordplay on many of them, especially 6d, 19d, 41a. Also some of the unclued words are not exactly those used in the named item?
Yes it is a synonym for weak clevertask - google the unclued lights together - they do all come under the same heading.
41a sneer(be scornful) backwards at the end of the clue?
Finished almost, including the anagram. Had never heard of him though. One letter missing, central one in 21ac never heard of this place either - gosh I'm ignorant!