Clear some spare time (5)
I believe the answer is:
overt
'clear' is the definition.
(both can mean apparent or obvious)
'some spare time' is the wordplay.
'some spare' becomes 'over' (left over).
'time' becomes 't' (abbreviation).
'over'+'t'='OVERT'
(Other definitions for overt that I've seen before include "Plain and obvious" , "Not concealed - public" , "Done in an obvious way" , "Open, up front" , "Open and candid" .)