Manual detonator (6)

I believe the answer is:

primer

This clue is a double definition.

'manual' is the first definition.
(thesaurus)

'detonator' is the second definition.
(thesaurus)

(Other definitions for primer that I've seen before include "device for detonating charge" , "Initial coat of paint" , "instructive book" , "Elementary textbook" , "Preparatory coat of paint" .)

I've seen this clue in the Sydney Morning Herald.

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