Train bore? (5)
I believe the answer is:
drill
I believe this clue is a double definition.
'train' is the first definition.
(drilling is a kind of training)
'bore?' is the second definition.
(thesaurus)
(Other definitions for drill that I've seen before include "Rehearsal of the procedure to be followed in an emergency" , "Tool for boring holes" , "Procedure - practice" , "DIY tool" , "makes one exercise" .)