Commissioned one tender with icy heart (7)
I believe the answer is:
officer
'commissioned one' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
'tender with icy heart' is the wordplay.
'tender' becomes 'offer' (synonyms).
'with' is an insertion indicator.
'icy heart' becomes 'ic' (I can't explain this - if you can you should believe this answer much more).
'offer' going around 'ic' is 'OFFICER'.
Can you help me to learn more?
(Other definitions for officer that I've seen before include "eg Colonel" , "served in the wardroom" , "General, for example" , "Commissioned member of the services" , "Police constable" .)