Lubricant's good — runs with lack of effort (6)
I believe the answer is:
grease
'lubricant's' is the definition.
(I've seen this before)
'good runs with lack of effort' is the wordplay.
'good' becomes 'g' (abbreviation).
'runs' becomes 'r' (cricket abbreviation).
'with' says to put letters next to each other.
'lack of effort' becomes 'ease' (I've seen this in another clue).
'g'+'r'+'ease'='GREASE'
(Other definitions for grease that I've seen before include "Lubricate (-ant)" , "Thick lubricant or frying oil" , "Mechanic (informal)" , "Fatty lubricant" , "Fully aware, astonished" .)