Opt to change container (3)
I believe the answer is:
pot
'container' is the definition.
(I know that pot is a type of container)
'opt to change' is the wordplay.
'to change' is an anagram indicator.
'opt' is an anagram of 'POT'.
(Other definitions for pot that I've seen before include "It sometimes calls the kettle black" , "Somewhere to go" , "prize" , "'A watched . . . never boils'" , "Slangy cannabis" .)