Tough old sea captain (5)
I believe the answer is:
hardy
'tough' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for hardy that I've seen before include "See 16" , "Author Thomas?" , "Robust - English novelist" , "Jude, Tess author" , "He wrote" .)