Having called Nola back in, go away (3,5)
I believe the answer is:
run along
'having called' is the definition.
I can't judge whether this defines the answer.
'nola back in go away' is the wordplay.
'back' says the letters should be written in reverse.
'in' indicates putting letters inside.
'go away' becomes 'rung' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'nola' backwards is 'alon'.
'alon' put into 'rung' is 'RUN ALONG'.
Can you help me to learn more?
(Other definitions for run along that I've seen before include "Informally leave or depart - on the trot?" , "Imperative for leaving" , "Go away!" .)