Struggles to get under one collection of invasive plants (5)
I believe the answer is:
ivies
'collection of invasive plants' is the definition.
The definition and answer can be both plants as well as being plural nouns.
Maybe you can see an association between them that I can't see?
'struggles to get under one' is the wordplay.
'struggles' becomes 'vies' (to vie is to struggle or contend with).
'to get under' is a charade indicator (letters next to each other) (in a down clue, some letters go under others).
'one' becomes 'i' (Roman numeral).
'vies' put after 'i' is 'IVIES'.
Can you help me to learn more?
(Other definitions for ivies that I've seen before include "Climbing plants with evergreen leaves" , "Vines with evergreen leaves" , "Climbers" .)