Job opening (4)
I believe the answer is:
'job opening' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for slot that I've seen before include "Small opening, for a coin say" , "Narrow opening as in gaming machine" , "Space for coin or programme" , "Fit into puzzle" , "Scheduled time -- aperture for coins" .)