Salesman turns up with money! Time for a share (10)
I believe the answer is:
percentage
'a share' is the definition.
('percentage' can be a synonym of 'share')
'salesman turns up with money time for' is the wordplay.
'salesman' becomes 'rep' (I've seen this before).
'turns up' says the letters should be written backwards.
'with' says to put letters next to each other.
'money' becomes 'cent' (I've seen this before**).
'time for' becomes 'age' (I've seen this in other clues).
'rep' reversed gives 'per'.
'per'+'cent'+'age'='PERCENTAGE'
(Other definitions for percentage that I've seen before include "Proportion stated in hundredth parts" , "Proportion in each 100" , "cut?" , "Proportion, share" , "Maybe commission" .)