Hedonist’s heroic article about Yorkshire river (9)
I believe the answer is:
epicurean
'hedonist's' is the definition.
(I've seen this before)
'heroic article about yorkshire river' is the wordplay.
'heroic' becomes 'epic' (synonyms).
'article' becomes 'an' (indefinite article).
'about' means one lot of letters go next to another.
'yorkshire river' becomes 'ure' (river in Yorkshire).
'an' after 'ure' is 'urean'.
'epic'+'urean'='EPICUREAN'
(Other definitions for epicurean that I've seen before include "Foodie's" , "Hedonistic" , "pleasure-seeker" , "enjoyer of good food" , "expert at the table" .)