This cheese to be the right one inside (4)
I believe the answer is:
brie
'this cheese' is the definition.
(Brie is an example)
'be the right one inside' is the wordplay.
'the right' becomes 'r' (common abbreviation).
'one' becomes 'i' (Roman numeral).
'inside' indicates putting letters inside.
'r'+'i'='ri'
'be' placed around 'ri' is 'BRIE'.
'to' is the link.
(Other definitions for brie that I've seen before include "Round soft Fr. cheese" , "French cream cheese" , "Soft, creamy French cheese" , "Variety of cheese" , "cheese-producing region" .)