Grass and tree riddled with insects (7)
I believe the answer is:
timothy
'grass' is the definition.
(I know that timothy is a type of grass)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for timothy that I've seen before include "young Cratchit at length?" , "Bible book" , "Grass; boy's name" , "haymaker?" , "A grass; two NT books" .)