Dishes filled with Irish product from hen raised in farms (9)

'farms' is the definition.
(piggery is a kind of farm)

'dishes filled with irish product from hen raised' is the wordplay.
'dishes' becomes 'pies' (a pie is a meal or dish).
'filled with' indicates putting letters inside.
'irish' becomes 'IR' (abbreviation for Irish).
'product from hen' becomes 'egg' (hens lay eggs).
'raised' says the letters should be written in reverse (going up in a down clue).
'ir'+'egg'='iregg'
'iregg' backwards is 'ggeri'.
'pies' enclosing 'ggeri' is 'PIGGERIES'.

'in' acts as a link.