Shows crew's left no whiskey at sea (8)
I believe the answer is:
reflects
'shows' is the definition.
(reflecting is a kind of showing)
'crew's left no whiskey at sea' is the wordplay.
'no' is a deletion indicator.
'whiskey' becomes 'W' (phonetic alphabet: alpha, bravo, charlie etc.).
'at sea' indicates an anagram.
'crews'+'left'='crewsleft'
'crewsleft' with 'w' removed is 'cresleft'.
'cresleft' anagrammed gives 'REFLECTS'.
(Other definitions for reflects that I've seen before include "'Contemplates, considers (8)'" , "Mulls over" , "Thinks deeply like mirror?" , "Mirrors or meditates" , "Sends back, light say" .)