Dish mostly said to be rustic (8)
I believe the answer is:
pastoral
'be rustic' is the definition.
(synonyms)
'dish mostly said' is the wordplay.
'dish mostly' becomes 'past' (I can't justify this - if you can you should give a lot more credence to this answer).
'said' becomes 'oral' (both can mean spoken).
'past'+'oral'='PASTORAL'
'to' is the link.
Can you help me to learn more?
(Other definitions for pastoral that I've seen before include "To do with shepherds, or concerned with spiritual guidance" , "Of shepherds or spiritual guides" , "Relating to rural life" , "Well-known symphony" , "Bucolic, rural" .)