Mark and Ian wandering on the street (5)
I believe the answer is:
stain
'mark' is the definition.
(synonyms)
'ian wandering on the street' is the wordplay.
'wandering' indicates anagramming the letters.
'on' means one lot of letters goes inside another (as in clothing \'on\' a person).
'the street' becomes 'st' ().
'ian' with letters rearranged gives 'ain'.
'ain' placed around 'st' is 'STAIN'.
'and' is the link.
(Other definitions for stain that I've seen before include "Blot" , "Satin (anag.)" , "Stigma" , "Spot - shame" , "Blemish; colour (wood)" .)