Somerset runner with pretty top (7)
I believe the answer is:
execute
'top' is the definition.
Although both the answer and definition are verbs in their base form, I can't understand how they can define each other.
'somerset runner with pretty' is the wordplay.
'somerset runner' becomes 'exe' (I can't justify this - if you can you should give a lot more credence to this answer).
'with' says to put letters next to each other.
'pretty' becomes 'cute' (both can mean attractive).
'exe'+'cute'='EXECUTE'
Can you help me to learn more?
(Other definitions for execute that I've seen before include "Get it done" , "ice" , "Carry out; behead" , "Inflict capital punishment upon" , "Finish off" .)