Is he dear to a correspondent? (3)
I believe the answer is:
sir
'a correspondent?' is the definition.
The answer and definition can be both people as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'is he dear' is the wordplay.
I cannot really understand how this works, but
'he' could be 'si' and 'si' is present in the answer.
A single letter 'r' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
'to' is the link.
Can you help me to learn more?
(Other definitions for sir that I've seen before include "Way to address gentleman" , "Title of knight or baronet" , "address to teacher" , "Male title of respect" , "Knight's prefix" .)