Dish of sturgeon occasionally expensive in France (8)
I believe the answer is:
trencher
'dish' is the definition.
(thesaurus)
'sturgeon occasionally expensive in france' is the wordplay.
'occasionally' means one should take alternating letters (letters taken at regular intervals or occasions).
'expensive in france' becomes 'cher' (I can't explain this - if you can you should give a lot more credence to this answer).
The alternate letters of 'sturgeon' are 'tren'.
'tren'+'cher'='TRENCHER'
'of' is the link.
Can you help me to learn more?
(Other definitions for trencher that I've seen before include "field worker" , "(Old) wooden platter for food" , "Board" , "bearer of food" , "one at digs?" .)