Found plough removed from Parisian fortress (4)
I believe the answer is:
base
'found' is the definition.
(I've seen this before)
'plough removed from parisian fortress' is the wordplay.
'plough' becomes 'till' (I've seen this before).
'removed from' is a deletion indicator.
'parisian fortress' becomes 'bastille' (I've seen this before).
'bastille' with 'till' removed is 'BASE'.
(Other definitions for base that I've seen before include "Foot; ignoble" , "Ignoble - foundation" , "Interest charged by the Bank of England to commercial banks" , "Lowest part; ignoble" , "Not a noble" .)