I hear you say I speak falsely about a citizen of a northern Atlantic republic (9)
I believe the answer is:
icelander
'i hear you say i speak falsely about a citizen of a northern' is the definition.
I can't tell whether this definition defines the answer.
'atlantic republic' is the wordplay.
I cannot quite see how this works, but
'atlantic republic' could be 'iceland' (I've seen this in another clue) and 'iceland' is present in the answer.
The remaining letters 'er' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for icelander that I've seen before include "Eg a person from Reykjavik" , "Nordic person" , "National" , "northerner" , "North Atlantic dweller" .)