Sound equipment covered by large light (4)
I believe the answer is:
lamp
'light' is the definition.
(lamp is a kind of light)
'sound equipment covered by large' is the wordplay.
'sound equipment' becomes 'amp' (amplifier).
'covered by' is a charade indicator (letters next to each other) (on top of in a down clue).
'large' becomes 'L' (eg in clothes sizes).
'amp' after 'l' is 'LAMP'.
(Other definitions for lamp that I've seen before include "Table light" , "Device for giving light on palm" , "Appliance producing light" , "Florence Nightingale was the Lady with the . . . ." , "Source of light, usually portable" .)