Roman legions, initially battered, showing standard (6)
I believe the answer is:
normal
'standard' is the definition.
(associated in meaning)
'roman legions initially battered' is the wordplay.
'initially' says to take the initial letters.
'battered' is an anagram indicator.
The initial letter of 'legions' is 'l'.
'roman'+'l'='romanl'
'romanl' anagrammed gives 'NORMAL'.
'showing' acts as a link.
(Other definitions for normal that I've seen before include "Average or ordinary" , "Conforming to a standard" , "Ordinary, not unusual" , "Accustomed" , "'Usual, typical (6)'" .)