Charm, a cross, close to chest (6)
I believe the answer is:
amulet
'charm' is the definition.
(I know that amulet is a type of charm)
'a cross close to chest' is the wordplay.
'cross' becomes 'mule' (a mule is a cross of a donkey and a horse).
'close to' says to take the final letters (the close/ending of).
The final letter of 'chest' is 't'.
'a'+'mule'+'t'='AMULET'
(Other definitions for amulet that I've seen before include "Thing worn as charm against evil" , "A type of lucky charm" , "Charm protecting against evil" , "Protective ornament" , "Magical charm" .)