Morgan pranged against English tree (8)
I believe the answer is:
mangrove
'tree' is the definition.
(mangrove is a kind of tree)
'morgan pranged against english' is the wordplay.
'pranged' is an anagram indicator.
'against' becomes 'v' (versus).
'english' becomes 'E' (abbreviation as in OED).
'morgan' with letters rearranged gives 'mangro'.
'mangro'+'v'+'e'='MANGROVE'
(Other definitions for mangrove that I've seen before include "Swamp tree" , "Tree of coastal swamps" , "Evergreen" , "that grows in swamps" , "Strange tree of tropical swamps is a veg, Norma" .)