Food given to disheartened boy who's filthy (6)
I believe the answer is:
grubby
'filthy' is the definition.
(thesaurus)
'food given to disheartened boy' is the wordplay.
'food' becomes 'grub' (grub can informally mean food).
'given to' says to put letters next to each other.
'disheartened' suggests removing the centre (the middle or heart is removed).
'boy' with its centre taken out is 'by'.
'grub'+'by'='GRUBBY'
'who's' is the link.
(Other definitions for grubby that I've seen before include "Soiled" , "Covered with ingrained dirt" , "Squalid" , "Dirty, could do with with a wash" , "Dirty, grimy" .)