Clean manure alternative on top of dirt (7)
I believe the answer is:
unarmed
'clean' is the definition.
(I've seen this in another clue)
'manure alternative on top of dirt' is the wordplay.
'alternative' is an anagram indicator (an alternative ordering of the letters).
'on top of' suggests taking the first letters.
The first letter of 'dirt' is 'd'.
'manure' with letters rearranged gives 'unarme'.
'unarme'+'d'='UNARMED'
(Other definitions for unarmed that I've seen before include "Weaponless" , "Lacking a weapon" , "Open" , "Not able to fire" , "Not able to go into battle" .)