Scent a traveller picked up (5)
I believe the answer is:
aroma
'scent' is the definition.
('aroma' can be a synonym of 'scent')
'a traveller picked up' is the wordplay.
'traveller' becomes 'mora' (I can't explain this - if you can you should give a lot more credence to this answer).
'picked up' says the letters should be written in reverse.
'a'+'mora'='amora'
'amora' written backwards gives 'AROMA'.
Can you help me to learn more?
(Other definitions for aroma that I've seen before include "Savour" , "Redolence" , "Perfume" , "Spicy fragrance" , "particular charm" .)