Study dance, having postponed payment once (8)
I believe the answer is:
contango
'postponed payment once' is the definition.
(historical type of stock exchange payment)
'study dance' is the wordplay.
'study' becomes 'con' (con can informally mean to study).
'dance' becomes 'tango' (tango is a kind of dance).
'con'+'tango'='CONTANGO'
'having' is the link.
(Other definitions for contango that I've seen before include "fee for postponement" , "Postponement of payment" .)