Dread losing time in blunder (5)
I believe the answer is:
error
'blunder' is the definition.
(thesaurus)
'dread losing time' is the wordplay.
'dread' becomes 'terror' (I've seen this before).
'losing' suggests deleting specific letters.
'time' becomes 't'.
'terror' with 't' taken out is 'ERROR'.
'in' acts as a link.
(Other definitions for error that I've seen before include "Slip-up" , "Blunder or mistake" , "heresy" , "Boob" , "Way of operating" .)