A runner up the pole? (4)
I believe the answer is:
bean
'a runner' is the definition.
The answer and definition can be both plants as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'up the pole?' is the wordplay.
'up' becomes 'bea' (I can't justify this - if you can you should give a lot more credence to this answer).
'the pole?' becomes 'n' (abbreviation for North, as in North Pole).
'bea'+'n'='BEAN'
Can you help me to learn more?
(Other definitions for bean that I've seen before include "It's often baked" , "Vegetable; head" , "coffee, perhaps" , "Kidney-shaped seed as for coffee" , "kept by the counter?" .)