Surgeon in Guard regularly fixed up messengers (7)

I believe the answer is:
runners
'up messengers' is the definition.
The answer and definition can be both people as well as being plural nouns.
Perhaps they are linked in a way I don't understand?
'surgeon in guard regularly fixed' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'fixed' indicates anagramming the letters.
'surgeon'+'in'+'guard'='surgeoninguard'
The alternate letters of 'surgeoninguard' are 'srennur'.
'srennur' is an anagram of 'RUNNERS'.
Can you help me to learn more?
(Other definitions for runners that I've seen before include "Shoots" , "They deliver messages on foot" , "Joggers" , "Horizontal branchs that produce new plants" , "messengers?" .)
