Degraded silt choking the plant (7)
I believe the answer is:
thistle
'plant' is the definition.
(type of plant)
'degraded silt choking the' is the wordplay.
I cannot quite understand how this works, but
an anagram of 'silt' is 'istl' which is present in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
The remaining letters 'he' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for thistle that I've seen before include "Prickly weed" , "Flower of Scotland" , "The list includes Scottish emblem" , "Scotland's emblem" , "Scotland's flower" .)