Old transport on river beyond the walls (10)
I believe the answer is:
extramural
'beyond the walls' is the definition.
I can't tell whether this defines the answer.
'old transport on river' is the wordplay.
'old' becomes 'ex'.
'transport on' becomes 'tram' (tram is a kind of transport. I am not sure about the 'on' bit.**).
'river' becomes 'ural' (I've seen this before).
'ex'+'tram'+'ural'='EXTRAMURAL'
Can you help me to learn more?
(Other definitions for extramural that I've seen before include "Off-premises (univ. studies)" , "outside the university" , "outside the building" , "What may be a wide painting" , "Taking place off campus?" .)