Proud tirade in favour of public transport (11)
I believe the answer is:
protuberant
'proud' is the definition.
(I've seen this before)
'tirade in favour of public transport' is the wordplay.
I cannot really see how this works, but
'tirade' could be 'rant' (both can mean an angry outburst) and 'rant' is present in the answer.
'of' could be 'o' and 'o' is found in the answer.
'transport' could be 'tube' (the London Underground is nicknamed the Tube) and 'tube' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for protuberant that I've seen before include "Sticking out" , "Proud" , "Outstanding" , "Bulging" .)