Street car going around traffic jam (4)
I believe the answer is:
tram
'street car' is the definition.
'tram' can be an answer for 'car' (as in a tram car). I am not certain of the 'street' bit.
'going around traffic jam' is the wordplay.
'going around traffic' becomes 't' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'jam' becomes 'ram' (synonyms).
't'+'ram'='TRAM'
Can you help me to learn more?
(Other definitions for tram that I've seen before include "Former public vehicle" , "Street vehicle running on rails" , "Streetcar" , "Passenger vehicle on rails" , "The Luas, say" .)