Go across for a small pie (8)
I believe the answer is:
turnover
'a small pie' is the definition.
(I've seen this before)
'go across' is the wordplay.
'go' becomes 'turn' ('turn' can be a synonym of 'go'**).
'across' becomes 'over' ('over' can be a synonym of 'across').
'turn'+'over'='TURNOVER'
'for' acts as a link.
(Other definitions for turnover that I've seen before include "Small pastry case - gross revenue" , "The amount of money taken by a business in a particular period" , "Folded pie" , "patisserie product" , "Total sales or rate of replenishment" .)