It's what I'd call an expensive girlfriend (4)
I believe the answer is:
dear
'an expensive girlfriend' is the definition.
The answer and definition can be both people as well as being singular nouns.
Maybe you can see a link between them that I can't see?
'it's what i'd call' is the wordplay.
I cannot really see how this works, but
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is present in the answer.
The remaining letters 'dar' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for dear that I've seen before include "Expensive or loved" , "polite form of address" , "close" , "love" , "pet > ducks" .)