What you might need to go beyond Dover? (8)
I believe the answer is:
passport
'what you might need' is the definition.
I can't judge whether this definition defines the answer.
'go beyond dover?' is the wordplay.
'go beyond' becomes 'pass' (synonyms).
'dover?' becomes 'port' (Dover is a port).
'pass'+'port'='PASSPORT'
'to' is the link.
(Other definitions for passport that I've seen before include "Travel identification" , "Travel doc" , "Official document required for foreign travel" , "that may gain acceptance" , "Carte blanche" .)