Deer almost zip over long grass (6)
I believe the answer is:
bamboo
'long grass' is the definition.
'deer almost zip over' is the wordplay.
'deer' becomes 'bambi' (deer in the Disney film Bambi).
'almost' means to remove the last letter (most of the word but not all of it).
'zip' becomes 'o' (zip can mean zero).
'over' becomes 'o' (cricket abbreviation**).
'bambi' with its final letter removed is 'bamb'.
'bamb'+'o'+'o'='BAMBOO'
(Other definitions for bamboo that I've seen before include "Tall woody plant" , "stick" , "Woody tropical grass with a hollow stem" , "Panda's staple diet" , "Woody grass plant" .)