On the street I run activity (4)
I believe the answer is:
stir
'activity' is the definition.
(thesaurus)
'on the street i run' is the wordplay.
'on' says to put letters next to each other.
'the street' becomes 'st'.
'run' becomes 'r' (cricket abbreviation).
'st'+'i' is 'sti'.
'sti'+'r'='STIR'
(Other definitions for stir that I've seen before include "Arouse; mix" , "Excite emotionally" , "Mix or agitate" , "Excitement" , "Prison - mix" .)