Eccentric Ottawan consumes dairy product (7)
I believe the answer is:
ricotta
'dairy product' is the definition.
(ricotta is a kind of dairy product)
'eccentric ottawan consumes' is the wordplay.
'consumes' indicates a hidden word (the answer has been consumed by the clue).
'RICOTTA' can be found hidden inside 'eccentric ottawan'.
(Other definitions for ricotta that I've seen before include "Italian curd cheese" , "cheese found" , "one brought on board?" , "Soft white cheese used in Italian cooking" , "Sheep's milk cheese" .)