Article on foot is a crime (5)
I believe the answer is:
theft
'crime' is the definition.
(theft is a kind of crime)
'article on foot' is the wordplay.
'article' becomes 'the' (the definite article in English).
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'foot' becomes 'ft' (abbreviation).
'the'+'ft'='THEFT'
'is a' is the link.
(Other definitions for theft that I've seen before include "Crime of stealing" , "Pilferage" , "Unlawful taking" , "Job" , "Illegal act of taking" .)