Purgative (5,5)
I believe the answer is:
epsom salts
'purgative' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for epsom salts that I've seen before include "They should clear out!" , "a purge" , "Medicinal preparation" , "Medicine taken for heartburn and constipation" , "Purgative" .)