1) Device 2) Generic school grp 3) Letters at end of page 4) Local school assoc 5) Page bottom notation 6) Patent and Trademark Office 7) Power takeoff 8) School-based group 9) WWII inits Found on https://www.crosswordclues.com/clue/pto
Power Take Off. A splined shaft at the front or rear of a tractor used to supply power to attachments such as mowers or power harrows. Standard speeds are 540 & 1000 rpm. Found on https://www.encyclo.co.uk/local/20496