Pulse of Aussie runner raised in stages (7)
I believe the answer is:
legumes
'pulse' is the definition.
(I've seen this before)
'aussie runner raised in stages' is the wordplay.
'aussie runner' becomes 'emu' (Australian bird that runs).
'raised' shows that the letters should be reversed in order (going up in a down clue).
'in' is an insertion indicator.
'stages' becomes 'legs' ('leg' can be a synonym of 'stage').
'emu' reversed gives 'ume'.
'ume' going into 'legs' is 'LEGUMES'.
'of' acts as a link.
(Other definitions for legumes that I've seen before include "Peas, beans, and lentils" , "Plants that bear their seeds in pods" , "Pulse" .)