williamseal, I was using BRB as shorthand for Big Red Book, aka Chambers. Apologies for being obscure.
The other resources I alluded to were TEA Crossword Helper and Word Web:
https://tea-crossword-helper.soft112.com/
https://wordweb.info/
I believe both currently offer free trials. I am far from expert in their use, and don't use them all the time, by any means, but they do help in certain circumstances.
TEA is handy if you know a certain number of letters in an answer but not necessarily their location. So, for 24d, for example, if you are confident of X, L and V, but nothing else, if you type in ";xlv..." it will show all words containing those three letters in any order. Only two show up in the Edited English list, one of which is the answer. It has many other features too.
WordWeb allows you to search whichever dictionaries you have loaded into it for particular text. Chambers is one option, the Oxford Dictionary of English is another. Should you not know any letters, but you want to search on a definition, if you search for all entries containing the words "Ganges" and "boat" for 6a, you will see only two qualifying entries, both beginning with P. One is your answer.
It also has a powerful anagram solver, and allows searching with wildcards. So, again on 24d, if you search for "v?x???" it will give you just five possibilities in Chambers, one of which is what you are looking for.
I have no connection with either product, and of course it's entirely up to you whether you wish to pay for them. Some people might consider using such help unethical. I make no comment on that, but as I've said before, I don't submit anyway. All I would say is that "ninja" solvers who can crack puzzles like this on a Friday night are unlikely to be unaware of such aids.