Without opening, study container (3)
I believe the answer is:
Here is my best explanation:
'container' is the definition.
(can is a kind of container)
'without opening study' is the subsidiary indication.
'without opening' means to remove the first letter.
'study' becomes 'scan'.
'scan' with its first letter taken off is 'can'.
(Other definitions for can that I've seen before include "Billy", "Metallic container", "Vessel", "Is able to; tin", "(Tin) container", "prison", "Are up to", "depth charge", "Possesses ability" and "Is able; container".)