Prepare celebration for old-fashioned person (4)
I believe the answer is:
dodo
'old-fashioned person' is the definition.
(dodo can informally mean an old-fashioned person)
'prepare celebration' is the wordplay.
'prepare' becomes 'do' (I've seen this in other clues).
'celebration' becomes 'do' (I've seen this in other clues).
'do'+'do'='DODO'
'for' is the link.
(Other definitions for dodo that I've seen before include "Bird (whose style of very out of fashion)" , "Idiot" , "one finished?" , "One deeply reactionary" , "Square" .)