Fences fool put up to protect ladies in trouble (9)
I believe the answer is:
palisades
'fences' is the definition.
('palisade' can be a synonym of 'fence')
'fool put up to protect ladies in trouble' is the wordplay.
'fool' becomes 'sap' ('sap' can be a synonym of 'fool'**).
'put up' says the letters should be written backwards.
'to protect' means one lot of letters goes inside another.
'in trouble' is an anagram indicator.
'sap' backwards is 'pas'.
'ladies' anagrammed gives 'lisade'.
'pas' going around 'lisade' is 'PALISADES'.
(Other definitions for palisades that I've seen before include "Fortifications of strong stakes in the ground" , "Strong fences for defence" , "Fences of stakes" .)