Question Author
Many thanks to polly-bubblebub - johnalex - Sandy wroe.I could never have worked out "cyan" although there is a connection with cyanide!
as for 'pay attention' I got it firmly stuck in my head that it was 'HEED......
Incidentally whilst trawling this site I noticed that loads of clues from the same X-word were answered whereas I had worked out all the others.I feel rather chuffed that my 85 years old "little grey cells" are still in reasonably good shape. Still , I will seriously consider consulting all you clever people another time! Much appreciation !