Approach filthy place on the outskirts of Lille (5)
I believe the answer is:
style
'approach' is the definition.
(I've seen this in another clue)
'filthy place on the outskirts of lille' is the wordplay.
'filthy place' becomes 'sty' (I've seen this in other clues).
'on' means one lot of letters go next to another.
'the outskirts of' means to remove the middle letters (letters on the edges or outskirts are used).
'lille' with its middle taken out is 'le'.
'sty'+'le'='STYLE'
(Other definitions for style that I've seen before include "Panache" , "Cut dash" , "Manner or look" , "Method; elegance" , "term" .)