Show half of cumulative returns (5)
I believe the answer is:
evita
'show' is the definition.
(I've seen this before)
'half of cumulative returns' is the wordplay.
'half of' means to take half the letters.
'returns' says the letters should be written in reverse.
'cumulative' with half the letters taken is 'ative'.
'ative' reversed gives 'EVITA'.
(Other definitions for evita that I've seen before include "1996 musical film, starring Madonna" , "Juan Peron's wife" , "Andrew Lloyd Webber musical set in Argentina" , "Nineteen Dn musical" , "Well-known musical" .)