Pulses initially rejected as food (4)
I believe the answer is:
eats
'food' is the definition.
(eats can mean food)
'pulses initially rejected' is the wordplay.
'pulses' becomes 'beats' ('beat' can be a synonym of 'pulse').
'initially rejected' means to remove the first letter.
'beats' with its initial letter removed is 'EATS'.
'as' acts as a link.
(Other definitions for eats that I've seen before include "Devours - food" , "meal" , "Scoffs" , "Takes nourishment" , "Consumes or dines" .)