I'd seen a new flavour (7)
I believe the answer is:
aniseed
'flavour' is the definition.
(I've seen this before)
'i'd seen a new' is the wordplay.
'new' indicates an anagram.
'id'+'seen'+'a'='idseena'
'idseena' with letters rearranged gives 'ANISEED'.
(Other definitions for aniseed that I've seen before include "taste of Pernod, perhaps?" , "Strong flavour" , "Liquorice flavour" , "Strong herbal flavouring" , "Pernod flavouring" .)