Dull, small travellers (11)
I believe the answer is:
pedestrians
'dull small travellers' is the definition.
'pedestrians' can be an answer for 'travellers' (pedestrian is a kind of traveller). I'm unsure of the 'dull small' bit.
'dull small travellers' is the wordplay.
'dull' becomes 'pedestrian' ('pedestrian' can be similar in meaning to 'dull').
'small travellers' becomes 's' (I am not sure about this - if you are sure you should believe this answer much more).
'pedestrian'+'s'='PEDESTRIANS'
Can you help me to learn more?
(Another definition for pedestrians that I've seen is " those making slow progress?".)