British tree died: another tree showing rot (10)
I believe the answer is:
balderdash
'rot' is the definition.
(I've seen this in another clue)
'british tree died another tree' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'tree' becomes 'alder' (alder is a kind of tree).
'died' becomes 'd' (abbreviation next to the year of someone's death).
'another tree' becomes 'ash' (ash is a kind of tree. I am not sure about the 'another' bit.).
'b'+'alder'+'d'+'ash'='BALDERDASH'
'showing' acts as a link.
Can you help me to learn more?
(Other definitions for balderdash that I've seen before include "bull" , "Codswallop" , "Rubbish" , "Poppycock" , "cobblers > GAME" .)