Lacking in quantity or quality (6)
I believe the answer is:
meagre
This clue is a double definition.
'lacking in quantity' is the first definition.
(I've seen this before)
'quality' is the second definition.
(I have seen 'Poor quality' mean 'meagre' so perhaps 'quality' could also mean 'meagre')
(Other definitions for meagre that I've seen before include "Small, insufficient" , "Stingy - thin" , "skinny" , "Scarce - scanty" , "deficient in amount" .)