I just 'replaced the clutch in my 2010 Subaru outback. 2 weeks later no reverse. The car has 89000 miles. Does this normally happen?

The clutch and reverse are unrelated. The only way they could be a connection would be if the mechanic somehow damaged the shifter linkage.

Engaging reverse requires the greatest mechanical displacement of the hydraulic/mechanical system. Does the clutch engagement point of the pedal travel seem much LOWER than before? If so, then you don't quite have enough action to catch reverse (without grinding). Have your wrench check for air in the system (unlikely), alignment of the slave cylinder pin, etc. If you need just a bit more push ask him to SLIGHTLY reduce the play at the master cylinder pushrod screw (it's just behind the accelerator pedal); a full turn or so will be enough too tighten up the geometry. Lastly, Subaru's design assumes that the tolerances of all the clutch components are reasonably tight so that pedal geometry ends up somewhere in the middle of the range. If you've used (aftermarket?) any part that's thicker or thinner you can end up with too much play at the pedal (loosing reverse/first), or too little (shorter clutch life). Parts production sloppiness was such that some NEW manual trans Subies were undrivable, as short folks couldn't get the pedal to the floor. Whenever a client presents a stick Subie for my care I try to fudge the pedal geometry to engage about half way down, allowing shifting by very short drivers. A lower geo is great for tall drivers...so long as they depress fully so as to get into reverse without much "chinking". Hope this helps.