Month before start of refit for vessel (8)
I believe the answer is:
decanter
'vessel' is the definition.
(decanter is a kind of vessel)
'month before start of refit' is the wordplay.
'month' becomes 'dec' (Dec is an example).
'before' becomes 'ante' (I've seen this before).
'start of' says to take the initial letters.
The initial letter of 'refit' is 'r'.
'dec'+'ante'+'r'='DECANTER'
'for' is the link.
(Other definitions for decanter that I've seen before include "Ornamental bottle for dispensing wine" , "Stoppered glass container for alcohol" , "Serving bottle for liquor" , "Recanted about glass bottle for wine" , "Glass container for table wine" .)