Start to teach (8)
I believe the answer is:
initiate
I believe this is a double definition.
'start' is the first definition.
('initiate' can be a synonym of 'start')
'teach' is the second definition.
(thesaurus)
'to' is the link.
(Other definitions for initiate that I've seen before include "Get cracking on" , "Admit into closed society - beginner" , "Start - trigger" , "Start, begin" , "Begin or admit into a closed society" .)