I can go on and on about European travelling from place to place (9)
I believe the answer is:
Here is my best explanation:
'travelling from place to place' is the definition.
'i can go on and on about european' is the subsidiary indication.
'can' becomes 'tin' ('tin' can be a synonym of 'can'**).
'go on and on' becomes 'rant'.
'about' means one lot of letters go next to another.
'european' becomes 'e' (abbreviation e.g. EU).
'rant' after 'e' is 'erant'.
(Other definitions for itinerant that I've seen before include "Traveller", "travelling from place to place", "(Person) on the move", "Rambling", "Nomad", "Old labourer/traveller who travelled from place to place", "Moving from place to place", "Wandering from place to place", "Tramp" and "Wanderer".)