Big glass boat (8)
I believe the answer is:
schooner
This clue might be a double definition.
'big glass' is the first definition.
'schooner' can be an answer for 'glass' (I've seen this before). I am not certain of the 'big' bit.
'boat' is the second definition.
(schooner is a kind of sailing vessel)
Can you help me to learn more?
(Other definitions for schooner that I've seen before include "In the main it is" , "Large beer or sherry glass" , "wooden vessel" , "Measure for sherry or kind of sailing ship" , "Sailing vessel used in former times" .)