Partly cleared leaves climbing on this tree? (5)
I believe the answer is:
elder
'this tree?' is the definition.
(elder is a kind of tree)
'partly cleared leaves climbing' is the wordplay.
'partly' indicates the answer is hidden within the clue (part of the clue is used).
'climbing' shows that the letters should be reversed in order (in a down clue, letters climb up).
'redle' is hidden in the letters of 'cleared leaves'.
'redle' written backwards gives 'ELDER'.
'on' acts as a link.
(Other definitions for elder that I've seen before include "Small tree with purple berries" , "Senior - church official" , "Woody shrub - used for wine, tea or cordial" , "Senior churchman - shrub" , "Senior tribal figure" .)