Ship requires check in before this .. (8)
I believe the answer is:
schooner
'ship' is the definition.
(I've seen this before)
'check in before this' is the wordplay.
'check' becomes 'ch' (abbreviation).
'in' indicates putting letters inside.
'before this' becomes 'sooner' (before the current time).
'ch' going within 'sooner' is 'SCHOONER'.
'requires' acts as a link.
(Other definitions for schooner that I've seen before include "boat" , "Sailing vessel - drinking vessel" , "that carries sherry" , "Two-master; a glass" , "In the main it is" .)