Traffic snarl (3)
'traffic snarl' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for jam that I've seen before include "Preserve - predicament" , "awful traffic" , "problem" , "Sweet stuff for bread - stuff it in" , "Spread; improvise (jazz)" .)
(Other definitions for tieup that I've seen before include "Connection with" , "Business association" .)