Divide group chasing sound purchase (6)
I believe the answer is:
bisect
'divide' is the definition.
(I've seen this before)
'group chasing sound purchase' is the wordplay.
'group' becomes 'sect' (I've seen this in other clues**).
'chasing' means one lot of letters go next to another.
'sound' shows a homophone (sound like).
'purchase' becomes 'buy' ('buy' can be a synonym of 'purchase').
'buy' is a homophone of 'bi'.
'sect' after 'bi' is 'BISECT'.
(Other definitions for bisect that I've seen before include "Cut twenty [IN TWO]" , "cross" , "Cut in half" , "Divide into two equal parts" , "Split exactly in two" .)