Captain Hook was so alone! (6-6)
I believe the answer is:
single-handed
'alone' is the definition.
(thesaurus)
'captain hook was' is the wordplay.
I cannot really see how this works, but
'hook' could be 'hand' (synonyms) and 'hand' is found in the answer.
This explanation may well be incorrect...
'so' acts as a link.
Can you help me to learn more?
(Other definitions for single-handed that I've seen before include "Glen dashed in (anag) -- entirely alone" , "Unaided" , "Without assistance" , "Done without help from others" , "Working alone" .)