I would use an [Edit] button which would be visible inside the cell. A click on the edit button would display the content in plain text format (assuming that the entire cell is a link) in a Text area or a TextBox. This would enable the user to mark content, copy and paste without having to worry about the link.
When being in edit mode, I would provide three new buttons below the editable area to enable the user to [Copy] the text and/or [Save] or [Cancel] the edit.
I have provided an optional answer in the mockup, if the user shouldn't be able to edit the link text (thanks to Vitalys comment).
download bmml source – Wireframes created with Balsamiq Mockups
A right click could work for computers, but it would not work on touch interfaces, so lets leave the right click out of the equation.