Niftiest (7)
I believe the answer is:
neatest
'niftiest' is the definition.
('neat' can be a synonym of 'nifty')
This is all the clue.
(Other definitions for neatest that I've seen before include "Most tidy" , "Seat ten (anag)" , "Most orderly" , "Most smart" , "best-looking desk, say?" .)