New shirt dean spoilt (9)
I believe the answer is:
tarnished
'spoilt' is the definition.
(tarnished can mean dirtied or spoilt)
'new shirt dean' is the wordplay.
'new' indicates an anagram.
'shirt'+'dean'='shirtdean'
'shirtdean' with letters rearranged gives 'TARNISHED'.
(Other definitions for tarnished that I've seen before include "Sullied" , "Having lost lustre" , "Stained" , "Blemished" , "Dulled, discoloured" .)