Interference with signal in northern French department? (5)
I believe the answer is:
noise
'interference' is the definition.
(I know that interference can be written as noise)
'northern french department?' is the wordplay.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'french department?' becomes 'Oise' (I've seen this before).
'n'+'oise'='NOISE'
'with signal in' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for noise that I've seen before include "Uproar" , "Loud or disturbing sound" , "Fuss" , "Unwanted sound" , "Loud or unpleasant sound" .)