The alchemist conceals cure (4)
I believe the answer is:
heal
'cure' is the definition.
(synonyms)
'the alchemist conceals' is the wordplay.
'conceals' indicates the answer is hidden within the clue.
'HEAL' can be found hidden inside 'the alchemist'.
(Other definitions for heal that I've seen before include "Restore to health" , "remedy" , "Of wound, mend and get better" , "Make better" , "Get healthy again" .)