Plant parasite almost engulfing top of tree (5)
I believe the answer is:
lotus
'plant' is the definition.
'parasite almost engulfing top of tree' is the wordplay.
'parasite' becomes 'louse' (I've seen this before).
'almost' means to remove the last letter (most of the word but not all of it).
'engulfing' means one lot of letters goes inside another.
'top of tree' becomes 't' (I can't explain this - if you can you should give a lot more credence to this answer).
'louse' with its final letter taken away is 'lous'.
'lous' going around 't' is 'LOTUS'.
Can you help me to learn more?
(Other definitions for lotus that I've seen before include "reason for indolence" , "Aquatic plant" , "Reason for forgetfulness" , "Sacred Egyptian water lily" , "Kind of cross-legged position for meditation" .)