Hardy expert supports Durham (7)
I believe the answer is:
durable
'hardy' is the definition.
(I've seen this before)
'expert supports durham' is the wordplay.
'expert' becomes 'able' (I've seen this in other clues).
'supports' means one lot of letters go next to another (bottom letters provide a support for the top ones).
'durham' becomes 'dur' (short for Durham).
'able' after 'dur' is 'DURABLE'.
(Other definitions for durable that I've seen before include "Good" , "Rugged; long-lasting" , "Made to last" , "Firm" , "Likely to last" .)