Vanish (2,7)
There are a few possibilities for this:
go missing
'vanish' is the definition.
(I know that vanish can be written as evaporate)
This is all the clue.
(Other definitions for evaporate that I've seen before include "vanish" , "Change from liquid to gas" , "Desiccate, dry up" , "Disappear into thin air" , "Fade away gradually" .)
'vanish' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for disappear that I've seen before include "exit" , "Pass out of sight" , "Do a bunk" , "Fade out" , "Melt away" .)