Rather strange to have a table inside a table cell... but let's have try.
If there is no need to compare the contents of the item lists in multiple rows, then you could work with a popover: Click on the "more" button and display an overlay containing all items including descriptions. The popover can have a small triangle pointing to the cell it originates from, and disappears when the user clicks outside of it (if there's nothing interactive inside, maybe there as well).
Depending on whether the user needs to see the "other fields" in the same row, place the popover either to the right (hiding the other fields) or above or below the item list cell (not hiding the other fields, but slightly strange placement).
If you tell us more about the users and their goals, we may be able to give better hints.
EDIT: Because you replied "with large amount of data, that's why tables looks like nice choice to represent this data", let me make this point: The larger the amount of data becomes, the less likely it is that a table is a good, user- and goal-supporting choice. I design for data in the millions, and the best approach here is to make the system smart enough to find the interesting rows and only show them.
How to determine what is interesting to the user depends a lot on your business: Sometimes it can be supported by ad-hoc filters, it could mean predefined filters which generate alerts, or maybe you have good statistics (or a smart AI already) to single out the unusual cases. Displaying only them relieves the user from searching/browsing through large tables.
