Cellists forking out for small gifts (8,7)
I believe the answer is:
stocking fillers
'small gifts' is the definition.
(small presents in Christmas stockings)
'cellists forking out' is the wordplay.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'cellists'+'forking'='cellistsforking'
'cellistsforking' with letters rearranged gives 'STOCKING FILLERS'.
'for' acts as a link.
(Other definitions for stocking fillers that I've seen before include "ladies' legs?" , "Pins" , "presents?" , "Present items" .)