Send out Vegemite sandwiches (4)
I believe the answer is:
emit
'send out' is the definition.
(I've seen this before)
'vegemite sandwiches' is the wordplay.
'sandwiches' says the answer is hidden in the clue (the answer is sandwiched in by the clue).
'EMIT' is hidden in the letters of 'vegemite'.
(Other definitions for emit that I've seen before include "Give out or pour forth" , "'Give out, light say (4)'" , "Release" , "Produce and discharge" , "'Give off, odour say (4)'" .)