Old guards about to get settled (6)
I believe the answer is:
agreed
'settled' is the definition.
(thesaurus)
'old guards about' is the wordplay.
'old' becomes 'aged' ('aged' can be similar in meaning to 'old').
'guards' means one lot of letters goes inside another.
'about' becomes 're' (regarding**).
'aged' enclosing 're' is 'AGREED'.
'to get' is the link.
(Other definitions for agreed that I've seen before include "came to the same conclusion" , "Corresponded" , "Done!" , "Saw eye to eye" , "Mutually settled" .)