Fizzy claret has new middle (7)
I believe the answer is:
central
'middle' is the definition.
(similar in meaning)
'fizzy claret has new' is the wordplay.
'fizzy' is an anagram indicator (I've seen this in other clues).
'has' is an insertion indicator.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'claret' anagrammed gives 'cetral'.
'cetral' placed around 'n' is 'CENTRAL'.
(Other definitions for central that I've seen before include "Middle; crucial" , "Most important, principal" , "Focal" , "Near the middle" , "Every answer here has one such letter" .)