Monkey causing some flurry in the market (8)
I believe the answer is:
marmoset
'monkey' is the definition.
(I know that marmoset is a type of New World monkey)
'some flurry in the market' is the wordplay.
'flurry' is an anagram indicator (I've seen 'flurried' mean this).
'in the' is an insertion indicator.
'market' becomes 'mart' (synonyms).
'some' anagrammed gives 'mose'.
'mose' inserted within 'mart' is 'MARMOSET'.
'causing' is the link.
(Other definitions for marmoset that I've seen before include "Small South American monkey" , "Primate" , "Turn morse mat over for the monkey" , "Small bushy-tailed monkey" , "Take me to arms about bushy-tailed monkey of tropical America" .)