Muse about contents of topsoil collected (4)
I believe the answer is:
clio
'muse' is the definition.
(Clio is an example)
'about contents of topsoil collected' is the wordplay.
'about' is a reversal indicator.
'contents of' indicates a hidden word.
'oilc' can be found hidden inside 'topsoil collected'.
'oilc' written backwards gives 'CLIO'.
(Other definitions for clio that I've seen before include "one historically inspiring" , "1 across's Muse - from Renault?" , "In Greek and Roman myth, the Muse of history" , "Muse of history (from Renault?)" , "one of nine sisters" .)