Moody, volatile (13)
I believe the answer is:
temperamental
I believe this clue is a double definition.
'moody' is the first definition.
(I know that moody can be written as temperamental)
'volatile' is the second definition.
(I've seen this before)
(Other definitions for temperamental that I've seen before include "requiring delicate handling" , "Liable to mood swings" , "Difficult" , "Unreliable" , "Touchy, moody" .)