。
I saw an amazing animal trick at the circus.
Literal
I [topic-は] circus [at-で] splendid animal [of-の] trick [object-を] saw.
見事 ('splendid, magnificent, brilliant') is a common na-adjective for praising performances or outcomes — the etymology relates to '見ること' (something worth seeing). 動物の芸 stacks possessive の to mean 'animals' tricks/performances.' で marks サーカス as the location where the seeing happened.