Plant a wee pet's maltreated (5,3)
I believe the answer is:
sweet pea
'plant' is the definition.
(sweet pea is a kind of plant)
'a wee pet's maltreated' is the wordplay.
'maltreated' indicates anagramming the letters.
'a'+'wee'+'pets'='aweepets'
'aweepets' with letters rearranged gives 'SWEET PEA'.
(Other definitions for sweet pea that I've seen before include "Peseta we paid for climbing garden flower" , "Climbing pant" , "Fragrant climber" , "Climbing plant with fragrant flowers" , "Fragrant flower" .)