Gang leader’s girl touring cool part of France (6-8)
I believe the answer is:
alsace-lorraine
'part of france' is the definition.
(I've seen this before)
'gang leader's girl' is the wordplay.
'gang leader's' becomes 'alsace' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'girl' becomes 'lorraine'.
'alsace'+'lorraine'='ALSACE-LORRAINE'
'touring cool' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
(Other definitions for alsace-lorraine that I've seen before include "border area" , "French region, lost 1871" .)