Stargazing device from earl's boat rebuilt (9)
I believe the answer is:
astrolabe
'stargazing device' is the definition.
(astronomical instrument)
'earl's boat rebuilt' is the wordplay.
'rebuilt' is an anagram indicator.
'earls'+'boat'='earlsboat'
'earlsboat' with letters rearranged gives 'ASTROLABE'.
'from' is the link.
(Other definitions for astrolabe that I've seen before include "Early astronomical instrument" , "Navigational device" , "heavenly model" , "Navigation aid" , "Old instrument for astronomical measurements" .)