It's not cheap, darling (4)
I believe the answer is:
dear
I believe this clue is a double definition.
'it's not cheap' is the first definition.
(I've seen this in another clue)
'darling' is the second definition.
(I know that darling can be written as dear)
(Other definitions for dear that I've seen before include "Expensive -- honey" , "Expensive - address" , "polite form of address" , "Honey - costly" , "Expensive; sweet" .)