Search if found in street (4)
I believe the answer is:
sift
'search' is the definition.
(thesaurus)
'if found in street' is the wordplay.
'found in' indicates putting letters inside.
'street' becomes 'st'.
'if' put within 'st' is 'SIFT'.
(Other definitions for sift that I've seen before include "Use a sieve" , "Separate by passing through fine mesh" , "Remove lumps from, eg, flour" , "Examine (eg evidence) discriminatingly" , "Sieve finely" .)