Formicary (7)
I believe the answer is:
anthill
'formicary' is the definition.
(I know that formicary can be written as anthill)
This is the entire clue.
(Other definitions for anthill that I've seen before include "Home to thousands" , "Nest" , "There's much work to be done here" , "Many a worker here" , "Built-up colony" .)