Tree with less on top? Not initially (5)
I believe the answer is:
alder
'tree' is the definition.
(I know that alder is a type of tree)
'less on top? not initially' is the wordplay.
'less on top?' becomes 'balder' (I've seen this before).
'not initially' means to remove the first letter.
'balder' with its first letter taken off is 'ALDER'.
'with' acts as a link.
(Other definitions for alder that I've seen before include "Birch relative" , "Tree or shrub whose wood is resistant to underwater rot" , "Shrub or tree with cone-like fruits" , "One [TYPE OF TREE]" , "Forward movement" .)