Hint please for Radial 31.
I've spent the last 2 days on this! I have a "solution" ( Copper sulphide minerals) which fits the word play (3 letter synonym for 'fit', 4 letter synonym for 'ceremony'). But that doesn't fit the definition.
I think the definition is the first word. Take a word for fit (noun, common in crosswords), with 'when cancelling a' leading to … . Put this before your word for ceremony.
Glad I could help, Cass - and glad that you've finished it off. Sometimes we have to work so hard to get convoluted, tricky clues that we don't recognise the simpler ones lurking amongst them!