Strip naked in backstreet toilet (7)
I believe the answer is:
latrine
'toilet' is the definition.
(latrine is a kind of toilet)
'strip naked in backstreet' is the wordplay.
'strip' becomes 'slat' (slat is a kind of strip).
'naked' indicates the central letters (outside letters removed so centre is unclothed).
'in backstreet' becomes 'trine' (I can't justify this - if you can you should give a lot more credence to this answer).
The central letters of 'slat' are 'la'.
'la'+'trine'='LATRINE'
Can you help me to learn more?
(Other definitions for latrine that I've seen before include "Camp lavatory" , "Lavatory (in barracks)" , "A military lavatory" , "Reliant on military loo" , "Toilet in a military area" .)