Two soldiers are enormous (5)
I believe the answer is:
giant
'enormous' is the definition.
(I've seen this before)
'two soldiers' is the wordplay.
'two soldiers' means two replacements for 'soldier'.
'soldier' becomes 'gi' (term for US soldier).
'soldier' becomes 'ant' (soldier is a type of ant).
'gi'+'ant'='GIANT'
'are' acts as a link.
(Other definitions for giant that I've seen before include "Extremely tall person" , "Titan" , "James Dean film (big one!)" , "Superhuman being" , "Monster" .)