Expensive ducks (4)
I believe the answer is:
dear
I believe this clue is a double definition.
'expensive' is the first definition.
(similar in meaning)
'ducks' is the second definition.
(both are affectionate terms of address)
(Other definitions for dear that I've seen before include "Costly (but loved!)" , "Overpriced" , "Needing plenty of bread" , "Treasured" , "Expensive or loved" .)