if its the old 7D, I don't think it will work. I have tried that camera out but didn't look at the card compartment. IIRC it takes a single Compact Flash card. However, the new 7D Mark II is styled after the 5dIII, so it should have both a CF slot as well as an SD slot. The 70D, which you mentioned in another thread, takes a single SD card, like my 'cheapie' full frame, the 6D.
Amazing that the dinosaur engineering the Compact Flash card is, that it has held on for this long. Tough old gunfighter.
Adorama has great customer service and return policies so if it doesn't work out you should be able to send it back no problem.