Leave container inside - it shows great restraint (10)
I believe the answer is:
abstinence
'restraint' is the definition.
(thesaurus)
'leave container inside' is the wordplay.
'leave' becomes 'absence' (I can't justify this - if you can you should believe this answer much more).
'container' becomes 'tin' (tin is a kind of container).
'inside' means one lot of letters goes inside another.
'absence' going around 'tin' is 'ABSTINENCE'.
'it shows great' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for abstinence that I've seen before include "Staying away from" , "giving it up" , "Practice of refraining (from alcohol)" , "Temperance" , "Practice of refraining from indulging an appetite" .)