Departs eastern county in Ireland, say (7)
I believe the answer is:
declare
'say' is the definition.
(declaring is a kind of saying)
'departs eastern county in ireland' is the wordplay.
'departs' becomes 'd' (common abbreviation e.g. train timetables).
'eastern' becomes 'e'.
'county in ireland' becomes 'clare' (Irish county).
'd'+'e'+'clare'='DECLARE'
(Other definitions for declare that I've seen before include "... cut short innings" , "Make clearly known" , "Announce formally" , "State emphatically" , "Aver, state" .)