More vacuous European politician leading bank (7)
I believe the answer is:
emptier
'more vacuous' is the definition.
('empty' can be a synonym of 'vacuous')
'european politician leading bank' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'politician' becomes 'mp'.
'leading' says to put letters next to each other.
'bank' becomes 'tier' (I've seen this before).
'e'+'mp'+'tier'='EMPTIER'
(Other definitions for emptier that I've seen before include "Being more hungry" , "more in need of food" , "I'm Peter (anag)" , "More vacuous" , "Containing less" .)