Buyer's first chat about consignment (5)
I believe the answer is:
batch
'consignment' is the definition.
(I've seen this before)
'buyer's first chat about' is the wordplay.
'buyer's first' becomes 'b' (1st letter of 'buyer').
'about' is an anagram indicator.
'chat' is an anagram of 'atch'.
'b'+'atch'='BATCH'
(Other definitions for batch that I've seen before include "Group of similar people" , "Quantity dealt with at one time" , "Arrange things in groups" , "Collection of items handled together" , "Set of items; instalment" .)