Charm a stubborn person tried first (6)
I believe the answer is:
amulet
'charm' is the definition.
(I know that amulet is a type of charm)
'a stubborn person tried first' is the wordplay.
'stubborn person' becomes 'mule' (I've seen this in another clue).
'tried first' becomes 't' (mst letter of 'tried').
'a'+'mule'+'t'='AMULET'
(Other definitions for amulet that I've seen before include "Charm worn to ward off evil" , "Jewel to protect from witchcraft" , "Charm worn against bad luck" , "that's charming" , "Protective trinket" .)