Football Association secures new site for celebration (6)
I believe the answer is:
fiesta
'celebration' is the definition.
(fiesta is a kind of celebration)
'football association secures new site' is the wordplay.
'football association' becomes 'fa' (abbreviation).
'secures' means one lot of letters goes inside another.
'new' indicates anagramming the letters.
'site' with letters rearranged gives 'iest'.
'fa' enclosing 'iest' is 'FIESTA'.
'for' acts as a link.
(Other definitions for fiesta that I've seen before include "Religious festival in Hispanic communities" , "Holiday; carnival" , "Saint's day; carnival" , "A Spanish public celebration" , "Outdoor celebration" .)