Mission San Antonio de Valero, more familiarly (5)
I believe the answer is:
alamo
(Other definitions for alamo that I've seen before include "Texas mission besieged and captured by Mexican forces in 1836" , "The --, Texan mission besieged in 1836" , "Texan battle" , "Where Davy Crockett died, 1836" , "Famous Texan mission" .)