Cook base for pilaf mainly in Greek style (5)
I believe the answer is:
doric
'greek style' is the definition.
'cook base for pilaf mainly' is the wordplay.
'cook' becomes 'do' (do can mean to cook).
'base for pilaf' becomes 'rice' (pilaf or pilau is a rice dish).
'mainly' means to remove the last letter (virtually or mainly the word, but not all of it).
'rice' with its final letter removed is 'ric'.
'do'+'ric'='DORIC'
'in' is the link.
(Other definitions for doric that I've seen before include "One classical order in architecture" , "Type of column" , "A classical style of architecture with fluted columns" , "Style of column" , "Greek dialect" .)