A beast of burden has time for charm (6)
I believe the answer is:
amulet
'charm' is the definition.
(amulet is a kind of charm)
'a beast of burden has time' is the wordplay.
'beast of burden' becomes 'mule' (I've seen this before).
'has' means one lot of letters go next to another.
'time' becomes 't'.
'a'+'mule'+'t'='AMULET'
'for' is the link.
(Other definitions for amulet that I've seen before include "Small charm" , "that's charming" , "Magical charm" , "Ornament thought to give protection" , "Charm to protect from evil" .)