Used spices? That's a sign (6)
I believe the answer is:
pisces
'that's a sign' is the definition.
(Pisces is an example)
'used spices?' is the wordplay.
'used' indicates an anagram.
'spices' is an anagram of 'PISCES'.
(Other definitions for pisces that I've seen before include "Fish star sign" , "stars" , "Twelfth sign of the zodiac, the Fish" , "'Sign of the zodiac, the fish (6)'" , "Twelfth zodiacal sign" .)