Crossword Genius

Bovine expert a good many finally dismissed (7)

Ross

I believe the answer is:

'bovine' is the definition.
(thesaurus)

'expert a good many finally dismissed' is the wordplay.
'expert' becomes 'buff' (I've seen this before).
'good many' becomes 'lot' (a good many can mean a lot).
'finally dismissed' means to remove the last letter.
'lot' with its final letter taken away is 'lo'.
'buff'+'a'+'lo'='BUFFALO'

(Other definitions for buffalo that I've seen before include "A hairy", "Wild animals", "American bison or related beast", "NY port; --- Bill (Cody)", "Large wild ox".)