American dye used before a party season's from this US city (8,7)
I believe the answer is:
colorado springs
'this us city' is the definition.
(I've seen this before)
'american dye used before a party season's' is the wordplay.
'american dye' becomes 'color' (US spelling of 'colour').
'used before' means one lot of letters go next to another.
'party' becomes 'do' (do can informally mean a party).
'season's' becomes 'spring's' (spring is a season).
'color'+'a'+'do'+'springs'='COLORADO SPRINGS'
'from' is the link.
(Other definitions for colorado springs that I've seen before include "American resort" , "US city" , "City on the eastern edge of the Rockies" , "US Air Force base" , "US resort" .)