Thanks Malone. I wouldn’t have continued this one without help, namely your post way back at #10.
I think it would have been nice to say clash cells contain multiple letters before obeying the instructions. The ‘numbers in brackets are lengths of grid entries’ was a hint, but not strong enough for the challenge presented. For me that spoiled a great puzzle. I remember very recently a Listener preamble clearly saying some cells would contain multiple letters.