Whale of an ace, etc, played (8)
I believe the answer is:
cetacean
'whale' is the definition.
(I've seen this before)
'an ace etc played' is the wordplay.
'played' is an anagram indicator.
'an'+'ace'+'etc'='anaceetc'
'anaceetc' is an anagram of 'CETACEAN'.
'of' acts as a link.
(Other definitions for cetacean that I've seen before include "Eg, whale, dolphin, etc" , "Member of the animal order containing whales and dolphins" , "Generic name for whale, dolphin or porpoise" , "Animal order including whales and dolphins" , "Encase cat with mammals like whales and dolphins" .)