Look — a ghost about to disappear! (6)
I believe the answer is:
aspect
'look' is the definition.
(synonyms)
'a ghost about to disappear' is the wordplay.
I cannot quite understand how this works, but
'a' is present in the answer.
'about' could be 'c' (abbreviation for 'circa') and 'c' is present in the answer.
The remaining letters 'spet' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for aspect that I've seen before include "Viewpoint, feature to be considered" , "View - distinct feature" , "front" , "Point of view or appearance" , "The appearance presented" .)