Description of article found in Yorkshire's last mine (7)
I believe the answer is:
epithet
'description' is the definition.
(epithet is a kind of description)
'article found in yorkshire's last mine' is the wordplay.
'article' becomes 'the' (the 'definite article' part of speech).
'found in' indicates putting letters inside.
'last' indicates one should take the final letters.
'mine' becomes 'pit' (down the pit).
The last letter of 'yorkshire' is 'e'.
'e'+'pit'='epit'
'the' going inside 'epit' is 'EPITHET'.
'of' is the link.
(Other definitions for epithet that I've seen before include "nickname" , "Word describing" , "Sobriquet" , "Descriptive term or short phrase" , "The 23: an -- for Richard I" .)