It's by way of being an extract of caviare (3)
I believe the answer is:
via
'it's by way of' is the definition.
(via means by way of or by means of)
'an extract of caviare' is the wordplay.
'an extract of' says the answer is hidden in the clue (I've seen this in other clues).
'VIA' is hidden in the letters of 'caviare'.
'being' acts as a link.
(Other definitions for via that I've seen before include "A Roman way" , "Roman road" , "Passing through" , "Going through" , "By way of - in Latin" .)