Grub found in peat soil (4)
I believe the answer is:
eats
'grub' is the definition.
('eats' can be a synonym of 'grub')
'in peat soil' is the wordplay.
'in' indicates the answer is hidden within the clue.
'EATS' is hidden in the letters of 'peat soil'.
'found' acts as a link.
(Other definitions for eats that I've seen before include "Devours - food" , "Food (informal)" , "Is not any faster" , "Grazes perhaps" , "Gets tucked into the cake" .)