Pismires (4)
I believe the answer is:
ants
'pismires' is the definition.
('ant' can be a synonym of 'pismire')
This is all the clue.
(Other definitions for ants that I've seen before include "Inhabitants of a formicary" , "Six-foot insects" , "They live in a formicary" , "Busy little insects" , "Emmets" .)