1100 on returning craft, a river passenger transport (7)
I believe the answer is:
tramcar
'passenger transport' is the definition.
'tramcar' can be an answer for 'transport' (tramcar is a kind of transport). I am unsure of the 'passenger' bit.
'1100 on returning craft a river' is the wordplay.
'mm00' becomes 'mc' (I can't explain this - if you can you should give a lot more credence to this answer).
'on' says to put letters next to each other.
'returning' says the letters should be written backwards.
'craft' becomes 'art' (both can mean cunning or trickery).
'river' becomes 'r' (abbreviation for river).
'art' written backwards gives 'tra'.
'mc' put after 'tra' is 'tramc'.
'tramc'+'a'+'r'='TRAMCAR'
Can you help me to learn more?
(Other definitions for tramcar that I've seen before include "Electric transport" , "Electrical vehicle" , "Electrically driven public transport vehicle" , "Public street transport on rails" , "Passenger vehicle running on rails" .)