One Celt is spoilt for choice (9)
I believe the answer is:
selection
'for choice' is the definition.
(synonyms)
'one celt is spoilt' is the wordplay.
'spoilt' indicates anagramming the letters.
'one'+'celt'+'is'='oneceltis'
'oneceltis' with letters rearranged gives 'SELECTION'.
(Other definitions for selection that I've seen before include "Horse tipped for betting" , "Choice, pick" , "Act of choosing" .)