Musical instrument popular in Bordeaux (8)
I believe the answer is:
clarinet
'musical instrument' is the definition.
(clarinet is a kind of musical instrument)
'popular in bordeaux' is the wordplay.
'popular' becomes 'in'.
'in' is an insertion indicator.
'bordeaux' becomes 'claret' (I've seen this before).
'in' put inside 'claret' is 'CLARINET'.
(Other definitions for clarinet that I've seen before include "Source of music" , "It's for playing" , "Woodwind instrument - Artie Shaw played one" , "23 instrument" , "Single-reed straight-tubed instrument" .)