Tidy in one attempt (4)
I believe the answer is:
Here is my best explanation:
'tidy' is the definition.
('neat' can be a synonym of 'tidy')
'in one attempt' is the subsidiary indication.
'in' says the answer is hidden in the clue.
'neat' can be found hidden inside 'one attempt'.
(Other definitions for neat that I've seen before include "Cool - without a mixer", "Without a mixer", "Spick and span", "Taken without water", "Clean and tidy", "Smart", "Trim - tidy - without water", "Undiluted", "Tidy -- without water" and "Tidy and trim".)