Night light eats current - it's supposed to be a fashionable device (3,3)
I believe the answer is:
mod con
'supposed to be a fashionable device' is the definition.
I don't know anything about this answer so I cannot judge whether this works.
'night light eats current' is the wordplay.
'night light' becomes 'moon' (I've seen this before).
'eats' indicates putting letters inside.
'current' becomes 'dc'.
'moon' going around 'dc' is 'MOD CON'.
'it's' acts as a link.
Can you help me to learn more?
(Another definition for mod con that I've seen is " Modern convenience".)