Principle of European red wine bottles (5)
I believe the answer is:
tenet
'principle' is the definition.
(thesaurus)
'european red wine bottles' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'red wine' becomes 'tent' (type of Spanish wine).
'bottles' means one lot of letters goes inside another ('bottle' can mean to contain).
'e' inserted within 'tent' is 'TENET'.
'of' is the link.
(Other definitions for tenet that I've seen before include "Doctrine, dogma, belief" , "It's believed" , "Adiaphoron" , "A belief or credo - it's a palindrome" , "Belief - maxim" .)