Inadequate? Some agree, but not all (6)
I believe the answer is:
meagre
'inadequate?' is the definition.
(thesaurus)
'some agree but not all' is the wordplay.
'not all' says the answer is hidden in the clue.
'MEAGRE' is hidden within 'some agree but'.
(Other definitions for meagre that I've seen before include "Lean, thin" , "Skimpy and scarce" , "Inadequate, scanty" , "Poor in quality" , "Lean and scanty" .)