Fancy international reference ignoring leader (8)
I believe the answer is:
illusion
'fancy' is the definition.
(synonyms)
'international reference ignoring leader' is the wordplay.
'international' becomes 'i' (abbreviation eg in IMF).
'reference' becomes 'allusion' (allusion is a kind of reference).
'ignoring leader' means to remove the first letter.
'allusion' with its first letter taken off is 'llusion'.
'i'+'llusion'='ILLUSION'
(Other definitions for illusion that I've seen before include "Deceptive appearance" , "False appearance" , "Subjects under discussion" , "False belief or image, like mirage" , "Wrong belief or fancy, may be optical" .)