A wicked old dispeller of gloom (3,4)
I believe the answer is:
oil lamp
'gloom' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'a wicked old dispeller' is the wordplay.
I cannot quite understand how this works, but
'a' could be 'amp' (A is the symbol for the amp or ampere) and 'amp' is found within the answer.
'wicked' could be 'ill' (I've seen this in another clue) and 'ill' is found in the answer.
'old' could be 'o' (common abbreviation eg in OE for Old English) and 'o' is located in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'of' acts as a link.
Can you help me to learn more?
(Other definitions for oil lamp that I've seen before include "Early means of illumination" , "Light that burns kerosene" .)