The wish of one hiding in the matted reeds (6)
I believe the answer is:
desire
'the wish' is the definition.
(I've seen this before)
'one hiding in the matted reeds' is the wordplay.
I cannot quite see how this works, but
'one' could be 'i' (Roman numeral) and 'i' is located in the answer.
an anagram of 'reeds' is 'desre' which is located in the left over letters.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
'of' acts as a link.
Can you help me to learn more?
(Other definitions for desire that I've seen before include "Long for (something)" , "Covet" , "Want, wish for" , "Strong wish" , "Want strongly" .)