Pressed oil with a bit of vitamin E from this (5)
I believe the answer is:
olive
'this' is the definition.
The definition suggests a singular noun which matches the answer.
'pressed oil with a bit of vitamin e' is the wordplay.
'pressed' indicates anagramming the letters (the letters are pressed into a new order).
'with' is a charade indicator (letters next to each other).
'a bit of' suggests taking the first letters.
The initial letter of 'vitamin' is 'v'.
'oil' with letters rearranged gives 'oli'.
'oli'+'v'+'e'='OLIVE'
'from' acts as a link.
(Other definitions for olive that I've seen before include "Mediterranean tree-fruit - nice in martini" , "Bitter fruit" , "This branch is offered to show peace" , "Yellow-green colour like Mediterranean fruit" , "Girl's name; tree" .)