Just millions given to European bank (6)
I believe the answer is:
merely
'just' is the definition.
('merely' can be a synonym of 'just')
'millions given to european bank' is the wordplay.
'millions' becomes 'm' (abbreviation).
'given to' means one lot of letters go next to another.
'european' becomes 'e' (abbreviation e.g. EU).
'bank' becomes 'rely' (I've seen this before**).
'm'+'e'+'rely'='MERELY'
(Other definitions for merely that I've seen before include "Simply - only" , "Just one" , "'Only, and nothing more (6)'" .)