Technology holding up former pupil's death notice (4)
I believe the answer is:
obit
'death notice' is the definition.
(I've seen this in another clue)
'technology holding up former pupil's' is the wordplay.
'technology' becomes 'IT' (Information Technology).
'holding up' means one lot of letters go next to another (in a down clue, some letters go below others).
'former pupil' becomes 'OB' (abbreviation for 'Old Boy').
'it' put after 'ob' is 'OBIT'.
(Other definitions for obit that I've seen before include "Memorial biography (abbr)" , "Commemoration of a death (abbr)" , "newspaper article" , "Death notice in paper" , "Biographical death notice (abbr)" .)