Sly, going round the market astutely (7)
I believe the answer is:
smartly
'astutely' is the definition.
Both the definition and answer are adverbs. Perhaps you can see a link between them that I don't see?
'sly going round the market' is the wordplay.
'going round' means one lot of letters goes inside another (some letters go around others).
'the market' becomes 'mart' ('mart' can be a synonym of 'market').
'sly' going around 'mart' is 'SMARTLY'.
Can you help me to learn more?
(Other definitions for smartly that I've seen before include "at a brisk pace" , "How the chic are turned out" , "wasting no time" , "pronto" .)