Chuck’s missing 500 yen (4)
I believe the answer is:
'yen' is the definition.
(I've seen this in another clue)
'chuck's missing 500' is the wordplay.
'chuck' becomes 'ditch' (both can mean to abandon or throw away).
'missing' indicates named letters should be taken away.
'500' becomes 'D' (Roman numeral for 500).
'ditch' with 'd' taken out is 'ITCH'.
(Other definitions for itch that I've seen before include "Skin sensation; desire" , "great desire" , "Irritating sensation on skin" , "It must be scratched" , "cause irritation" .)