Ghostly light? (6,4)
I believe the answer is:
spirit lamp
'ghostly light?' is the definition.
'spirit lamp' can be an answer for 'light?' (spirit lamp is a kind of light). I'm not sure about the 'ghostly' bit.
'ghostly light?' is the wordplay.
'ghostly' becomes 'spirit' (I can't explain this - if you can you should give a lot more credence to this answer).
'light?' becomes 'lamp' (lamp is a kind of light).
'spirit'+'lamp'='SPIRIT-LAMP'
Can you help me to learn more?
(Other definitions for spirit lamp that I've seen before include "Meths-burning light" , "this'll lighten things up" .)