A wee pest deforming garden plant (5,3)
I believe the answer is:
sweet pea
'garden plant' is the definition.
(I've seen this before)
'a wee pest deforming' is the wordplay.
'deforming' indicates an anagram (I've seen 'deformed' mean this).
'a'+'wee'+'pest'='aweepest'
'aweepest' anagrammed gives 'SWEET PEA'.
(Other definitions for sweet pea that I've seen before include "Fragrant flower" , "Climbing garden plant - saw tepee (anag)" , "Climbing plant with fragrant flowers" , "Climbing pant" , "Climbing plant with butterfly-shaped flowers" .)