Volatile (9)
'volatile' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for mercurial that I've seen before include "Changeable in mood" , "Changing unpredictably" , "Temperamental" , "Erratic" , "Prone to sudden mood swings" .)
'volatile' is the definition.
(I know that volatile can be written as explosive)
This is the entire clue.
(Other definitions for explosive that I've seen before include "Fiery" , "Touchy" , "Eg, gelignite" , "Likely to cause anger or controversy" , "TNT, for example" .)
'volatile' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for flighty that I've seen before include "Capricious" , "Mentally giddy, in an aerial way perhaps" , "Frivolous - irresponsible" , "Fickle; erratic" , "Giddy-minded" .)