Cures with leash, perhaps (5)
I believe the answer is:
heals
'cures' is the definition.
(I know this)
'leash perhaps' is the wordplay.
'perhaps' indicates anagramming the letters.
'leash' anagrammed gives 'HEALS'.
'with' acts as a link.
(Other definitions for heals that I've seen before include "Makes well" , "Mends, recovers" , "Cures" , "Returns to health" .)