Seaman not entirely kind about trouble (6)
I believe the answer is:
sailor
'seaman' is the definition.
(I've seen this before)
'kind about trouble' is the wordplay.
'kind' becomes 'sor' (I can't justify this - if you can you should believe this answer much more).
'about' means one lot of letters goes inside another.
'trouble' becomes 'ail' (synonyms).
'sor' enclosing 'ail' is 'SAILOR'.
'not entirely' acts as a link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for sailor that I've seen before include "Sinbad, for example" , "Seafarer" , "One in the main" , "Jack" , "Tar, AB" .)