Call back to obtain a financial plan (6)
I believe the answer is:
budget
'a financial plan' is the definition.
(I've seen this before)
'call back to obtain' is the wordplay.
'call' becomes 'dub' (dubbing is a kind of calling).
'back' is a reversal indicator.
'to obtain' becomes 'get' ('get' can be a synonym of 'obtain').
'dub' written backwards gives 'bud'.
'bud'+'get'='BUDGET'
(Other definitions for budget that I've seen before include "Chancellor of the Exchequer's responsibility?" , "occasion for speech" , "Economy" , "spending money" , "Fiscal estimate" .)