Leak from European delegation (8)
I believe the answer is:
emission
'leak' is the definition.
(emit can mean to leak)
'european delegation' is the wordplay.
'european' becomes 'E' (abbreviation e.g. EU).
'delegation' becomes 'mission' (synonyms).
'e'+'mission'='EMISSION'
'from' is the link.
(Other definitions for emission that I've seen before include "Is in some (anag) - discharge" , "Release" , "it gets thrown out" , "Sending forth" , "Something given out" .)