Bit late now because I’ve sent it off but I realise I wasn’t 100% happy with my reasoning for my answer to 79A.
Heartlessly cheat Caledonian exchange (4)
I went with “heartlessly cheat” as TR(I)CK, which would then be TRCK, or TR(O)CK, Scots variant on truck, the ‘O’ removed and contributing to the Organic Message.
This was the only one I lacked confidence on. Thanks for any advice or opinions!