Requested losing piece be returned for lovesick princess (6)
I believe the answer is:
isolde
'lovesick princess' is the definition.
'Isolde' can be an answer for 'princess' (legendary princess). I am unsure of the 'lovesick' bit.
'requested losing piece be returned' is the wordplay.
'piece' indicates the answer is hidden within the clue.
'be returned' says the letters should be written backwards (I've seen 'being returned' mean this).
'edlosi' is hidden within 'requested losing'.
'edlosi' back-to-front is 'ISOLDE'.
'for' acts as a link.
Can you help me to learn more?
(Other definitions for isolde that I've seen before include "Soiled like Tristan's lover" , "Wagnerian heroine" , "Tristan's beloved" , "Tristan's lover, sadly soiled" , "princess of legend" .)