It's prickly buying or selling trousers (5)
I believe the answer is:
gorse
'it's prickly' is the definition.
(prickly plant)
'buying or selling trousers' is the wordplay.
'trousers' indicates the answer is hidden within the clue (to trouser can mean to steal or take).
'GORSE' is hidden in the letters of 'buying or selling'.
(Other definitions for gorse that I've seen before include "Prickly shrub with yellow flowers" , "Spiny yellow-flowered shrub" , "Welsh assembly" , "Spiky shrub" , "Wild evergreen shrub with yellow flowers and sharp thorns" .)