Stealing article, flees town at first (5)
I believe the answer is:
theft
'stealing' is the definition.
('theft' can be a synonym of 'stealing')
'article flees town at first' is the wordplay.
'article' becomes 'the' (the 'definite article' part of speech).
'at first' says to take the initial letters.
The first letters of 'flees town' is 'ft'.
'the'+'ft'='THEFT'
(Other definitions for theft that I've seen before include "Act of larceny" , "heavy crime" , "Action of stealing" , "Pilferage" , "Illegal act of taking" .)