Leave it as it is - again in the way (6)
I believe the answer is:
'the way' is the definition.
(street is a kind of way)
'leave it as it is again in' is the wordplay.
'leave' says the letters should be written backwards (I've seen 'left' mean this).
'it' becomes ''t' (abbreviation. e.g. in 'tis).
'as it is' becomes 'ets' (I can't justify this - if you can you should give a lot more credence to this answer).
'again' becomes 're' (prefix meaning 'again').
'in' is an insertion indicator.
'tets' back-to-front is 'stet'.
'stet' placed around 're' is 'STREET'.
Can you help me to learn more?
(Other definitions for street that I've seen before include "Tester in public road" , "See 17" , "City road" , "Tester (anag.)" , "Thoroughfare lined with buildings" .)