Not being used in tabloid leader (4)
I believe the answer is:
idle
'not being used' is the definition.
(I've seen this in another clue)
'in tabloid leader' is the wordplay.
'in' says the answer is hidden in the clue.
'IDLE' is hidden in the letters of 'tabloid leader'.
(Other definitions for idle that I've seen before include "Inactive - lied (anag)" , "Not used to work" , "not being engaged" , "Lazy - vain" , "Not busy" .)