Soldiers finished eating hot duck (7)
I believe the answer is:
redhead
'duck' is the definition.
(redhead is a kind of duck)
'soldiers finished eating hot' is the wordplay.
'soldiers' becomes 're' (Royal Engineers).
'finished' becomes 'dead' (I can't justify this - if you can you should believe this answer much more).
'eating' is an insertion indicator.
'hot' becomes 'h' (abbreviation eg on taps).
'dead' placed around 'h' is 'dhead'.
're'+'dhead'='REDHEAD'
Can you help me to learn more?
(Other definitions for redhead that I've seen before include "Ginger nut?" , "'Carrot top'" , "Person with rufous hair" , "Bluey" , "Blue Australian" .)