Good and thin — too hungry? (6)
I believe the answer is:
greedy
'too hungry?' is the definition.
(wanting too much food)
'good and thin' is the wordplay.
'good' becomes 'g' (abbreviation).
'and' is a charade indicator (letters next to each other).
'thin' becomes 'reedy' (as in a thin or reedy voice).
'g'+'reedy'='GREEDY'
(Other definitions for greedy that I've seen before include "Starving" , "pig!" , "Wanting too much" , "Grasping" , "Keen" .)