Companions of key soldiers with time succeeded (7)
I believe the answer is:
escorts
'companions' is the definition.
(I know this)
'key soldiers with time succeeded' is the wordplay.
'key' becomes 'esc' ('Escape' key on a computer keyboard).
'soldiers' becomes 'OR' (Other Ranks).
'with' says to put letters next to each other.
'time' becomes 't' (abbreviation).
'succeeded' becomes 's' (genealogical abbreviation).
'esc'+'or'+'t'+'s'='ESCORTS'
'of' is the link.
(Other definitions for escorts that I've seen before include "They accompany others" , "Accompanies, perhaps socially" , "Accompanies to protect" , "Attendants" , "Armed guards" .)