Cow possibly turned up Japanese coin under tree (8)
I believe the answer is:
alderney
'cow possibly' is the definition.
(Alderney is a type of cow)
'turned up japanese coin under tree' is the wordplay.
'turned up' says the letters should be written backwards.
'japanese coin' becomes 'yen' (I've seen this before).
'under' says to put letters next to each other.
'tree' becomes 'alder' (alder tree is a kind of tree**).
'yen' reversed gives 'ney'.
'ney' put after 'alder' is 'ALDERNEY'.
(Other definitions for alderney that I've seen before include "Channel isle" , "Third largest of the Channel Islands" , "One of Channel Islands" , "Cattle" , "Cow, perhaps" .)