Thanks, jono.
That was a difficult clue and I'd never seen "environs" as a containment indicator.
To be honest, I initially drew a blank. But then I looked up synonyms of "dormant" and the first 9-letter hit was a clear fit.
Yes, it's clunky and I doubt that many crossword editors would approve.
But most of my Clueless/PR/WPR entries are 💩, so I seldom cast aspersions in that department. 😂