Postulate with a cross inspired other men at the front (5)
I believe the answer is:
axiom
'postulate' is the definition.
(I've seen this in another clue)
'a cross inspired other men at the front' is the wordplay.
'cross' becomes 'x' (X is cross-shaped).
'at the front' says to take the initial letters.
The initial letters of 'inspired other men' is 'iom'.
'a'+'x'+'iom'='AXIOM'
'with' acts as a link.
(Other definitions for axiom that I've seen before include "Adage" , "Principle; assumption" , "Truism - proverb" , "Established principle" , "Self-evident statement" .)