In hope, at least, one can use it as a mulch (4)
I believe the answer is:
peat
'one can use it as a mulch' is the definition.
I can't judge whether this definition defines the answer.
'in hope at least' is the wordplay.
'in' indicates a hidden word.
'PEAT' is hidden in the letters of 'hope at least'.
Can you help me to learn more?
(Other definitions for peat that I've seen before include "Dried turf" , "It's used for fuel and in the garden" , "Fuel from marsh" , "Some got energy from this" , "Vegetable matter in bogs, like turf" .)