Oily sandwiches - key sodium source for browsers (4,4)
I believe the answer is:
salt lick
'sodium source for browsers' is the definition.
I can't judge whether this defines the answer.
'oily sandwiches key' is the wordplay.
'oily' becomes 'slick' (I've seen this in another clue).
'sandwiches' indicates putting letters inside (to sandwich is to block something in).
'key' becomes 'alt' (the Alt keyboard button).
'slick' going around 'alt' is 'SALT-LICK'.
Can you help me to learn more?
(Other definitions for salt lick that I've seen before include "Essential animal provision" , "source of mineral" .)