Lead in the French wood (5)
I believe the answer is:
leash
'lead' is the definition.
(I know that lead can be written as leash)
'the french wood' is the wordplay.
'the french' becomes 'le' ('the' in French).
'wood' becomes 'ash' (wood from an ash tree).
'le'+'ash'='LEASH'
'in' is the link.
(Other definitions for leash that I've seen before include "Restraint, tether" , "Strap for holding a dog while walking" , "Spanish city famous for swordmaking" , "Rope to control dog" , "Dog lead" .)