Rugged, durable (5)
I believe the answer is:
I believe this is a double definition.
'rugged' is the first definition.
(similar in meaning)
'durable' is the second definition.
(Other definitions for hardy that I've seen before include "Resistant to frost etc" , "Stalwart" , "Rugged; author" , "Author - robust" , "relatively able to endure exposure" .)