Center Controller reported an aircraft flew below the Minimum Vectoring Altitude due to an incorrect readback of the controller's clearance.

Narrative

Aircraft released via Redmond SID and heading 170. Pilot checked on after departure correctly and I issued 'radar contact; leaving 7;000 [direct] SUNBE (couple hundred miles south) and restated climb to 140;00.' Read back was marginal with '[direct] SUNBE; maintain 14;000'. No alt to make turn so my assumption is he's going direct now. I restated 'SUNBE at 7;000 please' and he said to effect 'garbled... sorry SUNBE cross 7;000 and then 14;000 after that.' Typically; the aircraft is not even close to our Minimum Vectoring Altitude to go on course if Tower ships them in a timely manner at that point. Typically the jet will be on course in around 12 to 15 miles from departure. While this was going on I had several VFR practice approaches and VFR aircraft so my attention was drawn to potential conflict. I called in the blind for VFR aircraft as well as Tower. Somehow I missed that this jet actually read back fix 'cross' at 7;000 which would never in my years have made sense. I'm surprised that the pilot did not query me. 7;000 feet for 200+ miles or something like that then climb? Despite being distracted with the conflict potential and the fact that I heard fix; alt and top alt I trusted what I heard was issued. After the pilot asked when I came back online from the Tower I realized what may have happened and at that point reissued top altitude and for him to continue climb to my next higher terrain. On my part; hearing the crossing word had implications for sure. On the pilot side; the responsibility of accepting a clearance should have some weight.