Animal like this seen in container (5)
I believe the answer is:
bison
'animal' is the definition.
(I've seen this before)
'like this seen in container' is the wordplay.
'like this' becomes 'so' ('like so').
'seen in' means one lot of letters goes inside another.
'container' becomes 'bin' (bin is a type of container).
'so' put into 'bin' is 'BISON'.
(Other definitions for bison that I've seen before include "Buffalo (US)" , "Wild ox of the prairies" , "Wild cow" , "Shaggy-haired wild ox" , "North American buffalo" .)