Consider changing gear en route (6)
I believe the answer is:
regard
'consider' is the definition.
(synonyms)
'changing gear en route' is the wordplay.
'changing' is an anagram indicator.
'en route' becomes 'rd' (I can't justify this - if you can you should believe this answer much more).
'gear' anagrammed gives 'rega'.
'rega'+'rd'='REGARD'
Can you help me to learn more?
(Other definitions for regard that I've seen before include "Think of" , "Gaze at; esteem" , "Judge" , "Concern" , "Relation to" .)