Cover up European cuts over energy (7)
I believe the answer is:
eclipse
'cover up' is the definition.
(thesaurus)
'european cuts over energy' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'cuts' becomes 'clips' (clip is a kind of cut).
'over' means one lot of letters go next to another (in a down clue, some letters go over others).
'energy' becomes 'e' (physics symbol as in E=mcl).
'e'+'clips'+'e'='ECLIPSE'
(Other definitions for eclipse that I've seen before include "Throw into shade, like a heavenly body" , "Overshadow, obscure" , "Dull time for male duck" , "Celestial obscuration of light" , "blackout" .)