Mission in Uppsala mobbed (5)
I believe the answer is:
alamo
'mission' is the definition.
(famous mission and siege from the Texas revolution)
'in uppsala mobbed' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ALAMO' is hidden within 'uppsala mobbed'.
(Other definitions for alamo that I've seen before include "The answer is a place of siege" , "Where Jim Bowie died" , "Famous Texan mission" , "1836 massacre at a San Antonio, Texas mission" , "Scene of massacre in Texas" .)