Seeds explorer's broadcast (4)
I believe the answer is:
oats
'seeds' is the definition.
(I have seen 'Edible seeds ' mean 'oats' so perhaps 'seeds' could also mean 'oats')
'explorer's broadcast' is the wordplay.
'explorer' becomes 'Oates' (Lawrence Oates, South Pole explorer).
'broadcast' shows a homophone (sound like) (how the word might sound on the radio or TV).
'oates' is a homophone of 'OATS'.
(Other definitions for oats that I've seen before include "Grain for porridge" , "Grains used as food and fodder" , "Basis of porridge" , "Porridge mix" , "Cereal for porridge" .)