Facial tissue additive (4)
I believe the answer is:
aloe
'facial tissue additive' 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 fruit" , "Succulent plant (4) 5532" , ". . . . vera, soothing plant" , "Succulent plant (may be bitter!)" , "Bitter drug from a leaf juice" .)