River and province on the borders of Lille (4)
I believe the answer is:
nile
'river' is the definition.
(Nile River is an example)
'province on the borders of lille' is the wordplay.
'province' becomes 'ni' (I've seen this in other clues).
'on' means one lot of letters go next to another.
'the borders of' says to hollow out the word (remove centre letters).
'lille' with its middle taken out is 'le'.
'ni'+'le'='NILE'
'and' is the link.
(Other definitions for nile that I've seen before include "White or Blue river of Africa" , "white flower?" , "Long river" , "African river" , "Current" .)