Thorny plants climbed up pole (5)
I believe the answer is:
roses
'thorny plants' is the definition.
(I've seen this before)
'climbed up pole' is the wordplay.
'climbed' becomes 'rose' (raise and climb can both mean to go up or increase).
'up pole' becomes 's' (abbreviation for South, as in South Pole. I am not sure about the 'up' bit.).
'rose'+'s'='ROSES'
Can you help me to learn more?
(Other definitions for roses that I've seen before include "chocolates" , "''. . . . . are red, violets are blue''" , "Flowers for watering cans?" , "Ramblers, for example" , "favours > certain wines" .)