Soldier like Montgomery principally as example (8)
I believe the answer is:
paradigm
'example' is the definition.
(paradigm is a kind of example)
'soldier like montgomery principally' is the wordplay.
'soldier' becomes 'para' (para is a kind of soldier**).
'like' becomes 'dig' (I've seen this in other clues).
'principally' suggests taking the first letters.
The first letter of 'montgomery' is 'm'.
'para'+'dig'+'m'='PARADIGM'
'as' is the link.
(Other definitions for paradigm that I've seen before include "Model or example for rapid agm" , "Pattern -conceptual framework" , "Example, model or pattern" , "Archetype" , "Framework or typical example" .)