Trigger (3,3)
'trigger' is the definition.
(synonyms)
This is all the clue.
(Other definitions for set off that I've seen before include "'Leave on a journey (3,3)'" , "Begin journey or detonate bomb" , "Start journey or detonate bomb" , "Begin journey or cause to explode" , "Leave on a journey or put in motion" .)
'trigger' is the definition.
(I know that trigger can be written as touch off)
This is the entire clue.
'trigger' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for detonate that I've seen before include "Trigger" , "let off" , "Set off explosive device" , "Blow up, explode" , "Discharge" .)