Schedule space (4)
I believe the answer is:
slot
'schedule space' 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 "Opening for coin or TV programme" , "Long narrow slit" , "Space for coin or programme" , "Scheduled time - hierarchical position" , "Scheduled time -- aperture for coins" .)