Regret being right about European writer (6)
I believe the answer is:
repent
'regret' is the definition.
(synonyms)
'right about european writer' is the wordplay.
'right' becomes 'rt'.
'about' is an insertion indicator.
'european' becomes 'E' (abbreviation e.g. EU).
'writer' becomes 'pen' (I've seen this before).
'e'+'pen'='epen'
'rt' going around 'epen' is 'REPENT'.
'being' acts as a link.
(Other definitions for repent that I've seen before include "Feel or express contrition" , "Be sorry for - . . . . . . ye sinners" , "Feel regret/remorse" , "Feel sorry" , "Feel guilty" .)