Not busy (4)
'not busy' is the definition.
('idle' is the opposite to 'busy')
This is all the clue.
(Other definitions for idle that I've seen before include "Do very little" , "Do nothing, laze" , "'Lazy, not doing anything (4)'" , "without basis" , "Lazy - unemployed" .)
'not busy' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for free that I've seen before include "At large" , "Available - for love" , "Costing nothing" , "unemployed" , "Not under restraint" .)