Key with modifiers to call certain behaviour in xmodmap

HW: Samsung N145 (10" netbook) OS: Xubuntu 14.10 Problem: Backspace key is not functioning. Want to make Backspace key behaviour be called by Ctrl+Del key combination. I guess it should be possible to achieve with xmodmap, but cannot find which way can i assign key with modifiers to call certain behaviour. Any ideas?

10x 4ward