Officials ultimately do nothing to hide European corruption (6)
I believe the answer is:
sleaze
'corruption' is the definition.
(I've seen this before)
'officials ultimately do nothing to hide european' is the wordplay.
'ultimately' says to take the final letters.
'do nothing' becomes 'laze' (laze around).
'to hide' means one lot of letters goes inside another.
'european' becomes 'E' (abbreviation e.g. EU).
The final letter of 'officials' is 's'.
'laze' going around 'e' is 'leaze'.
's'+'leaze'='SLEAZE'
(Other definitions for sleaze that I've seen before include "Cheap and vulgar behaviour" , "Immoral activities" , "Dishonest or immoral doings" , "'Cheapness, tackiness (6)'" , "Vulgarity" .)