Like a swamp with many plants (5)
I believe the answer is:
reedy
'like a swamp with many plants' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for reedy that I've seen before include "Sounding like eg oboe" , "(Of a person) tall and thin" , "Shrill, or piping" , "Long and thin" , "edge of some river-banks" .)