Time-sheet reveals network (4)
I believe the answer is:
mesh
'network' is the definition.
(I know that network can be written as mesh)
'time-sheet reveals' is the wordplay.
'reveals' indicates the answer is hidden within the clue.
'MESH' can be found hidden inside 'time sheet'.
(Other definitions for mesh that I've seen before include "Crossed wires" , "Netting made of wire or thread" , "Network fabric - engage with it" , "Interlock" , "Become entangled - become engaged" .)