Soldiers start to make fresh inroads (2-5)
I believe the answer is:
re-enter
'to make fresh inroads' is the definition.
I can't judge whether this defines the answer.
'soldiers start' is the wordplay.
'soldiers' becomes 're' (Royal Engineers).
'start' becomes 'enter' (I can't justify this - if you can you should believe this answer much more).
're'+'enter'='RE-ENTER'
Can you help me to learn more?
(Other definitions for re-enter that I've seen before include "Come back inside" , "Go back in" , "compete again" , "Come or go in again" .)