Trouble concerning leg when going over tree (8)
I believe the answer is:
magnolia
'tree' is the definition.
(magnolia is a kind of tree)
'trouble concerning leg when going over' is the wordplay.
'trouble' becomes 'ail' (synonyms).
'concerning' becomes 'on' (both can mean 'in relation to').
'leg when' becomes 'gam' (I can't justify this - if you can you should believe this answer much more).
'going over' says the letters should be written backwards.
'ail'+'on'+'gam'='ailongam'
'ailongam' back-to-front is 'MAGNOLIA'.
Can you help me to learn more?
(Other definitions for magnolia that I've seen before include "Creamy colour" , "Fragrant bloom and ubiquitous paint colour" , "Flowering tree; light pinkish white" , "bush" , "tree blossoms" .)