A Greek character allowed to display charm (6)
I believe the answer is:
amulet
'charm' is the definition.
(I know that amulet is a type of charm)
'a greek character allowed' is the wordplay.
'greek character' becomes 'mu' (letter of the Greek alphabet).
'allowed' becomes 'let' (to let is to allow or permit).
'a'+'mu'+'let'='AMULET'
'to display' acts as a link.
(Other definitions for amulet that I've seen before include "Protective jewellery" , "Small item of jewellery" , "Charm protecting against evil" , "lucky defender" , "Charm worn against bad luck" .)