Well-regulated (7)
I believe the answer is:
orderly
'well-regulated' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for orderly that I've seen before include "Systematically, not haphazard" , "Methodical, like soldier servant" , "Hospital attendant; well behaved" , "Hospital or military attendant" , "Regular - neat" .)