Quality of some grub in each can brought into dining room (9)
'quality of some grub' is the definition.
(quality of meat)
'each can brought into dining room' is the wordplay.
'each' becomes 'ea'.
'can' becomes 'tin' (synonyms).
'brought into' means one lot of letters goes inside another.
'dining room' becomes 'mess' (mess is a kind of dining room).
'eatin' put inside 'mess' is 'MEATINESS'.
'in' acts as a link.
(Other definitions for meatiness that I've seen before include "Brawniness; substance", "quality of beef?", "Depth of substance".)