Drama at sea with sick old creature (9)
I believe the answer is:
armadillo
'creature' is the definition.
(armadillo is a kind of creature)
'drama at sea with sick old' is the wordplay.
'at sea' indicates an anagram.
'with' is a charade indicator (letters next to each other).
'sick' becomes 'ill' (similar in meaning).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'drama' anagrammed gives 'armad'.
'armad'+'ill'+'o'='ARMADILLO'
(Other definitions for armadillo that I've seen before include "Insect eater" , "S. Am. plated mammal" , "armour-plated type" , "one of the Animals makes appearance" , "Toothless Native American" .)