Obscure European Community borders with Spain (7)
I believe the answer is:
eclipse
'obscure' is the definition.
(eclipsing is a kind of obscuring)
'european community borders with spain' is the wordplay.
'european community' becomes 'ec'.
'borders' becomes 'lips'.
'with' says to put letters next to each other.
'spain' becomes 'e' (abbreviation for Espana).
'ec'+'lips'+'e'='ECLIPSE'
(Other definitions for eclipse that I've seen before include "Heavenly phenomenon" , "Celestial phenomenon" , "Blot out" , "screen, more or less" , "Heavenly event; drake's time of dull plumage" .)