Stepped back: mud outside new Ruhr location (8)

'ruhr location' is the definition.
The definition suggests a singular noun which matches the answer.

'stepped back mud outside new' is the wordplay.
'stepped' becomes 'trod' ('tread' can be a synonym of 'step').
'back' shows that the letters should be reversed in order.
'outside' means one lot of letters goes inside another (some letters go outside others).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'trod' back-to-front is 'dort'.
'mud' placed around 'n' is 'mund'.
'dort'+'mund'='DORTMUND'

Can you help me to learn more?