My holding up benefits causes strain (6)
I believe the answer is:
melody
'strain' is the definition.
(I know that strain can be written as melody)
'my holding up benefits' is the wordplay.
'holding' means one lot of letters goes inside another.
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'benefits' becomes 'dole' (dole can mean government benefits).
'dole' written backwards gives 'elod'.
'my' placed around 'elod' is 'MELODY'.
'causes' acts as a link.
(Other definitions for melody that I've seen before include "Strain" , "Air, tune" , "My dole (anag.)" , "Sweet music, tuneful song" , "Musical theme" .)