Go back through, to take a look at (6)
I believe the answer is:
repair
'at' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'go back through to take a look' is the wordplay.
'go back' says the letters should be written backwards.
'through' becomes 'per' ('per' can mean through or by means of).
'to take' means one lot of letters go next to another.
'a look' becomes 'air' (something might have a certain air or look).
'per' backwards is 'rep'.
'rep'+'air'='REPAIR'
Can you help me to learn more?
(Other definitions for repair that I've seen before include "It may be effected by" , "service" , "Restore to good order" , "Mend, put right" , "Maintain" .)