Great entertainment? (7)
I believe the answer is:
titanic
'great' is the definition.
(thesaurus)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for titanic that I've seen before include "Iceberg-hitting ship" , "Hugely strong (but lost!)" , "Extremely large" , "Film success (1997) - ship disaster (1912)" , "like Oceanus" .)