Taught a new route in the borders of Thailand (7)
I believe the answer is:
tutored
'taught' is the definition.
(synonyms)
'a new route in the borders of thailand' is the wordplay.
'a new' indicates anagramming the letters.
'in the' means one lot of letters goes inside another.
'borders of' says to hollow out the word (remove centre letters).
'thailand' with its centre taken out is 'td'.
'route' with letters rearranged gives 'utore'.
'utore' inserted into 'td' is 'TUTORED'.
(Other definitions for tutored that I've seen before include "Gave private lessons to" , "Disciplined" , "Instructed" , "Trained" , "Rude tot (anag.)" .)