Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
prae-saepĭo (-sēpĭo), psi, ptum, 4, v. a., to fence in front, to block up, barricade (class.): aditus atque itinera trabibus, Caes. B. C. 1, 27: loca montuosa sublicis, id. ib. 3, 49: omni aditu praesaepto, id. B. G. 7, 77.
praesēpe, praesēpio, etc., v. praesaep-.