Mix up wet earth with roots of old laurel tree (6)
I believe the answer is:
muddle
'mix up' is the definition.
(muddling is a kind of mixing up)
'wet earth with roots of old laurel tree' is the wordplay.
'wet earth' becomes 'mud' (I've seen this before).
'with' says to put letters next to each other.
'roots of' suggests the final letters.
The final letters of 'old laurel tree' are 'dle'.
'mud'+'dle'='MUDDLE'
(Other definitions for muddle that I've seen before include "disorderly state of affairs" , "Confuse" , "Disorder, jumble" , "Confusion - mess" , "Clutter" .)