State of Delaware ignoring Washington over carbon (7)
I believe the answer is:
declare
'state' is the definition.
(I know that state is a more specific form of the action advise)
'delaware ignoring washington over carbon' is the wordplay.
'ignoring' is a deletion indicator.
'washington' becomes 'wa' (abbreviation for the US state).
'over' means one lot of letters goes inside another.
'carbon' becomes 'C' (chemical symbol).
'delaware' with 'wa' taken away is 'delare'.
'delare' placed around 'c' is 'DECLARE'.
'of' is the link.
(Other definitions for declare that I've seen before include "... cut short innings" , "say" , "State clearly, announce officially" , "Make clearly known" , "Proclaim" .)