Lime and cats affected plant (8)
I believe the answer is:
clematis
'plant' is the definition.
(clematis is a kind of plant)
'lime and cats affected' is the wordplay.
'and' says to put letters next to each other (I've seen this in other clues).
'affected' indicates an anagram.
'lime' put after 'cats' is 'catslime'.
'catslime' is an anagram of 'CLEMATIS'.
(Other definitions for clematis that I've seen before include "flower" , "Climbing garden plant" , "Climber's" , "Old man's beard" , "Popular climbing plant" .)