Commission centre-page spread (10)
I believe the answer is:
percentage
'commission' is the definition.
(I've seen this before)
'centre-page spread' is the wordplay.
'spread' is an anagram indicator.
'centre'+'page'='centrepage'
'centrepage' is an anagram of 'PERCENTAGE'.
(Other definitions for percentage that I've seen before include "Proportion in each 100" , "cut?" , "Proportion, share" , "Proportion stated in hundredth parts" , "Maybe commission" .)