Soldiers in time will give consent (5)
I believe the answer is:
agree
'consent' is the definition.
(agreeing is a kind of consenting)
'soldiers in time' is the wordplay.
'soldiers' becomes 're' (Royal Engineers).
'in' means one lot of letters goes inside another.
'time' becomes 'age' (age is a kind of time).
're' going within 'age' is 'AGREE'.
'will give' is the link.
(Other definitions for agree that I've seen before include "Enjoy view in common" , "'Assent, concur (5)'" , "share the same view" , "Consent required" , "Concur - correspond" .)