Slow voyages round the pole (6)
I believe the answer is:
snails
'slow voyages round the pole' is the definition.
I can't judge whether this defines the answer.
'voyages round the pole' is the wordplay.
'voyages' becomes 'sails' (sail is a kind of voyage).
'round' means one lot of letters goes inside another.
'the pole' becomes 'N' (abbreviation for North, as in North Pole).
'sails' enclosing 'n' is 'SNAILS'.
Can you help me to learn more?
(Other definitions for snails that I've seen before include "Air-breathing molluscs" , "oath" , "Soft-bodied animals with spiral shells, common in garden" , "Garden creatures" , "Gastropod molluscs" .)