Lacking the means (6)
I believe the answer is:
unable
'lacking the means' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for unable that I've seen before include "Impotent" , "Nebula (anag)" , "Not having the neccessary means" , "Lacking power (to do something)" , "Lacking the skill" .)