In NY a sole freshly cooked with onions (9)
I believe the answer is:
lyonnaise
'cooked with onions' is the definition.
(I've seen this before)
'in ny a sole freshly' is the wordplay.
'freshly' is an anagram indicator.
'in'+'ny'+'a'+'sole'='innyasole'
'innyasole' with letters rearranged gives 'LYONNAISE'.
(Other definitions for lyonnaise that I've seen before include "cooked in a way to make you cry?" , "(Of potatoes) cooked with onions in a wine sauce" , "cooking with onions" , "Served with onions" .)