Payload missing odd parts on second mission (5)
I believe the answer is:
alamo
'mission' is the definition.
(famous mission and siege from the Texas revolution)
'payload missing odd parts on second' is the wordplay.
'missing odd parts' means one should take alternating letters.
'on' is a charade indicator (letters next to each other).
'second' becomes 'mo' (both are short periods of time).
The alternate letters of 'payload' are 'ala'.
'ala'+'mo'='ALAMO'
(Other definitions for alamo that I've seen before include "US mission" , "Texas fort, scene of famous siege by Mexican army" , "Famous Texan fortress" , "Davy Crockett's last stand" , "Famous battle in Texas launched by the Mexican army" .)