A professional can take a set quickly (6)
I believe the answer is:
presto
'quickly' is the definition.
(I've seen this before)
'a professional can take a set' is the wordplay.
'a professional' becomes 'pro' (synonyms).
'can take' indicates putting letters inside.
'a set' becomes 'est' (I can't justify this - if you can you should believe this answer much more).
'pro' placed around 'est' is 'PRESTO'.
Can you help me to learn more?
(Other definitions for presto that I've seen before include "Immediately" , "Very fast (mus.)" , "at great speed..." , "In a quick tempo (music)" , "hey......,cries the magician" .)