Did less? Mostly this (4)
I believe the answer is:
idle
'this' is the definition.
The definition and answer are not the same part of speech.
'did less? mostly' is the wordplay.
'mostly' says the answer is hidden in the clue (most of the letters in the clue).
'IDLE' can be found hidden inside 'did less'.
Can you help me to learn more?
(Other definitions for idle that I've seen before include "-- Jack, pantomime character" , "Do nothing, laze" , "Not busy" , "Dormant" , "loiter aimlessly" .)