Excellent oil beaten to make mayonnaise (5)
I believe the answer is:
aioli
'mayonnaise' is the definition.
(mayonnaise seasoned with garlic)
'excellent oil beaten' is the wordplay.
'excellent' becomes 'ai' (resembles 'A1', old-fashioned term for excellent).
'beaten' is an anagram indicator (letters beaten up or destroyed).
'oil' anagrammed gives 'oli'.
'ai'+'oli'='AIOLI'
'to make' acts as a link.
(Other definitions for aioli that I've seen before include "Sort of mayonnaise" , "Garlicky mayonnaise" , "garlic sauce" , "mayonniase" , "garlic dip" .)