Plants gone wild within slanted line (8)
I believe the answer is:
begonias
'plants' is the definition.
(begonia is a kind of plant)
'gone wild within slanted line' is the wordplay.
'wild' is an anagram indicator.
'within' indicates putting letters inside.
'slanted line' becomes 'bias' (bias is a kind of line. I am not sure about the 'slanted' bit.).
'gone' anagrammed gives 'egon'.
'egon' inserted into 'bias' is 'BEGONIAS'.
Can you help me to learn more?
(Other definitions for begonias that I've seen before include "O begin as flowers" , "Nosebag I put on for the flowers" .)