One struggles to find climbing plants (5)
I believe the answer is:
ivies
'climbing plants' is the definition.
(I've seen this before)
'one struggles' is the wordplay.
'one' becomes 'i' (Roman numeral).
'struggles' becomes 'vies' (I've seen this in other clues).
'i'+'vies'='IVIES'
'to find' is the link.
(Other definitions for ivies that I've seen before include "Climbing plants with evergreen leaves" , "Vines with evergreen leaves" , "Climbers" .)