I'm very grateful that you've said that, S_Pugh. I'd entered an S in the 8th letter of the definition, but now that you say, I can see that D is much more suitable. So, the definition indicates past tense, therefore you're right : Y is a 7-letter word, the first word of Z.
You mentioned earlier about something starting from the first word of the definition to Y. And making the necessary changes to 3 letters in order to form a relevant 9-letter word results in all real words. That is surely no coincidence...