Rocky from a French stable (8)
I believe the answer is:
unsteady
'rocky' is the definition.
(I've seen this before)
'a french stable' is the wordplay.
'a french' becomes 'un' ('a' in French).
'stable' becomes 'steady' ('steady' can be similar in meaning to 'stable'**).
'un'+'steady'='UNSTEADY'
'from' acts as a link.
(Other definitions for unsteady that I've seen before include "likely to wobble" , "Wobbly" , "Precarious, insecure" , "not firmly fixed" , "Not safe" .)