Street set up trial runs (5)
I believe the answer is:
tests
'trial runs' is the definition.
'tests' can be an answer for 'runs' ('test' can be a synonym of 'run'). I'm not certain of the 'trial' bit.
'street set up' is the wordplay.
'street' becomes 'st'.
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'st'+'set'='stset'
'stset' backwards is 'TESTS'.
Can you help me to learn more?
(Other definitions for tests that I've seen before include "Trials to see if something works" , "Tries out" , "Critically examines" , "Examinations, trials" , "International cricket matches" .)