Ingredient in some soaps (4)
I believe the answer is:
aloe
'ingredient in some soaps' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for aloe that I've seen before include "Bitter drug from a leaf juice" , ". . . . vera, soothing plant" , "Fleshy-leaved plant" , "Genus of bitter herbs" , "Plant source of purgative drug" .)