Model soldier, like leader of mission (8)
I believe the answer is:
paradigm
'model' is the definition.
(paradigm is a kind of model)
'soldier like leader of mission' is the wordplay.
'soldier' becomes 'para' (para is a kind of soldier**).
'like' becomes 'dig' (I've seen this in other clues).
'leader of' suggests taking the first letters.
The initial letter of 'mission' is 'm'.
'para'+'dig'+'m'='PARADIGM'
(Other definitions for paradigm that I've seen before include "Epitome" , "Pattern -conceptual framework" , "Archetype" , "Adam grip (anag.)" , "Typical example or model (of something)" .)