Many peer at sea, to see the blue (8)
I believe the answer is:
empyrean
'the blue' is the definition.
(thesaurus)
'many peer at sea' is the wordplay.
'at sea' indicates anagramming the letters.
'many'+'peer'='manypeer'
'manypeer' is an anagram of 'EMPYREAN'.
'to see' acts as a link.
(Other definitions for empyrean that I've seen before include "The heavens (poetic)" , "vault of the sky, celestial heaven" , "The celestial vault or firmament" , "Heavenly (archaic)" , "May preen about the celestial vault" .)