European lair is delightful place (4)
I believe the answer is:
eden
'delightful place' is the definition.
(I've seen this before)
'european lair' is the wordplay.
'european' becomes 'e' (abbreviation e.g. EU).
'lair' becomes 'den' ('den' can be a synonym of 'lair').
'e'+'den'='EDEN'
'is' acts as a link.
(Other definitions for eden that I've seen before include "Delightful place" , "Paradise - ex-PM" , "The original garden?" , "Adam and Eve home" , "Former prime minister" .)