Glitch deleting time from alarm (5)
I believe the answer is:
error
'glitch' is the definition.
'time from alarm' is the wordplay.
'time' becomes 't'.
'from' indicates named letters should be taken away.
'alarm' becomes 'terror' (I've seen this before).
'terror' with 't' taken out is 'ERROR'.
'deleting' acts as a link.
I am not very happy about this link. It may belong to another bit of the clue.
(Other definitions for error that I've seen before include "1 down" , "Miscarriage of justice" , "Faux pas" , "Boob" , "Blunder or mistake" .)