Boredom in French island engulfing Greek character (5)
I believe the answer is:
ennui
'boredom' is the definition.
(I know that boredom can be written as ennui)
'in french island engulfing greek character' is the wordplay.
'in french' becomes 'en' ('in' in French).
'island' becomes 'i' (geographical abbreviation).
'engulfing' means one lot of letters goes inside another.
'greek character' becomes 'nu' (letter from the Greek alphabet).
'en'+'i'='eni'
'eni' placed around 'nu' is 'ENNUI'.
(Other definitions for ennui that I've seen before include "Low interest rate" , "Feeling of dissatisfaction" , "Boredom in France" , "depression" , "Boredom or discontent" .)