Potter in tabloid leader (4)
I believe the answer is:
idle
'potter' is the definition.
(thesaurus)
'in tabloid leader' is the wordplay.
'in' indicates the answer is hidden within the clue.
'IDLE' can be found hidden inside 'tabloid leader'.
(Other definitions for idle that I've seen before include "lndolent" , "-- Jack, pantomime character" , "Slothful" , "Frivolous" , "Useless" .)