Followers regret importing European metal (7)
I believe the answer is:
retinue
'followers' is the definition.
(retinue can mean an important person's followers)
'regret importing european metal' is the wordplay.
'regret' becomes 'rue' (to rue something is to regret it).
'importing' is an insertion indicator.
'european' becomes 'e' (abbreviation e.g. EU).
'metal' becomes 'tin' (tin is a kind of metal).
'e'+'tin'='etin'
'rue' enclosing 'etin' is 'RETINUE'.
(Other definitions for retinue that I've seen before include "Group of attendants for VIP" , "Train, escort" , "Band of attendants" , "Cortege" , "VIP's attendants" .)