Foreshadow Harbour finale (7)
I believe the answer is:
portend
'foreshadow' is the definition.
(I know that foreshadow can be written as portend)
'harbour finale' is the wordplay.
'harbour' becomes 'port' (I've seen this before).
'finale' becomes 'end' (the end of a story or show).
'port'+'end'='PORTEND'
(Other definitions for portend that I've seen before include "Be a sign of something to come" , "Omen" , "Be a sign of (impending calamity)" , "forecast" , "Presage, bode" .)