Medium's deck (5)
I believe the answer is:
tarot
'medium's deck' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tarot that I've seen before include "Card used for fortunetelling" , "one may have been taken from deck" , "Picture card" , "Cards often used in fortune-telling" , "These cards are used to tell fortunes" .)