Walks furtively up to unoccupied characters on board ship (6)
I believe the answer is:
sidles
'walks furtively' is the definition.
The definition and answer can be both to do with motion as well as being verbs in their -s form.
Maybe there's an association between them I don't understand?
'up to unoccupied characters on board ship' is the wordplay.
I cannot quite understand how this works, but
'unoccupied' could be 'idle' (similar in meaning) and 'idle' is located in the answer.
'ship' could be 'ss' (prefix in ship names eg SS Great Britain) and 'ss' is found within the leftover letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for sidles that I've seen before include "Moves sideways" , "Walks sideways like crab" , "Move sideways or furtively" , "Approaches obliquely" .)