Remove stability in a French joint (7)
I believe the answer is:
unhinge
'remove stability' is the definition.
'unhinge' can be an answer for 'remove' (unhinging is a kind of removing). I am unsure of the 'stability' bit.
'a french joint' is the wordplay.
'a french' becomes 'un' ('a' in French).
'joint' becomes 'hinge' (hinge is a kind of joint).
'un'+'hinge'='UNHINGE'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for unhinge that I've seen before include "Remove a gate from its support" , "Remove a door or derange" , "turn crazy" , "Drive mad in huge inn" , "Drive demented in huge inn" .)