Insipid, thin (6)
I believe the answer is:
watery
This clue is a double definition.
'insipid' is the first definition.
(I've seen this before)
'thin' is the second definition.
(similar in meaning)
(Other definitions for watery that I've seen before include "Overly diluted, thin" , "Aqueous" , "Weak, too diluted" , "Dilute; weak, pale" , "Insipid" .)