Comparatively smart tool (7)
I believe the answer is:
trimmer
I believe this clue is a double definition.
'comparatively smart' is the first definition.
('trim' can be a synonym of 'smart')
'tool' is the second definition.
(cutting tool)
(Other definitions for trimmer that I've seen before include "Hair clipper" , "Cutter; slimmer and fitter" , "horizontal beam" , "barber" , "Comparatively slender" .)