Regret holding European money for entourage (7)
I believe the answer is:
retinue
'entourage' is the definition.
('retinue' can be a synonym of 'entourage')
'regret holding european money' is the wordplay.
'regret' becomes 'rue' ('rue' can be a synonym of 'regret').
'holding' indicates putting letters inside.
'european' becomes 'e' (abbreviation e.g. EU).
'money' becomes 'tin' (I've seen this before**).
'e'+'tin'='etin'
'rue' enclosing 'etin' is 'RETINUE'.
'for' is the link.
(Other definitions for retinue that I've seen before include "Body of aides" , "Train, following" , "Figure out" , "Group of assistants" , "Personal staff" .)