Reversible boat (5)
I believe the answer is:
kayak
I believe this is a double definition.
'reversible' is the first definition.
'boat' is the second definition.
(I know that kayak is a more specific form of the action boat)
(Other definitions for kayak that I've seen before include "Type of canoe" , "Palindromic canoe used by eskimos" , "Small canoe used by Eskimo" , "Inuit's light canoe" , "Inuit boat" .)