Plant covering bottom of flower on a swamp (6)
I believe the answer is:
morass
'swamp' is the definition.
(I've seen this before)
'plant covering bottom of flower on a' is the wordplay.
'plant' becomes 'moss' (I've seen this in other clues).
'covering' indicates putting letters inside.
'bottom of' indicates one should take the final letters.
'on' says to put letters next to each other.
The last letter of 'flower' is 'r'.
'r'+'a'='ra'
'moss' placed around 'ra' is 'MORASS'.
(Other definitions for morass that I've seen before include "complicated situation" , "mess" , "Bog or swamp" , "Bog; confused situation" , "Confusion" .)