Interference in stable (6)
I believe the answer is:
static
I believe this is a double definition.
'interference' is the first definition.
(static is a kind of interference)
'stable' is the second definition.
(thesaurus)
'in' acts as a link.
(Other definitions for static that I've seen before include "Cast it (anag) - unmoving" , "Inactive, motionless" , "Inert or passive, like some electricity" , "showing no signs of going anywhere" , "Atmospheric disturbance" .)