Bare northern parts a Breton loved (9)
I believe the answer is:
unadorned
'bare' is the definition.
(thesaurus)
'northern parts a breton loved' is the wordplay.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'parts' is an insertion indicator (in the sense of cuts or separates).
'a breton' becomes 'un' ('a' in French - Brittany is in France).
'loved' becomes 'adored' (adoring is a kind of loving).
'un'+'adored'='unadored'
'n' going inside 'unadored' is 'UNADORNED'.
(Other definitions for unadorned that I've seen before include "Not decorated, plain and simple" , "Simple and plain as around den" , "Without embellishment" , "Plain, undecorated" .)