Claim provided by small investor (5)
I believe the answer is:
saver
'investor' is the definition.
(I've seen this before)
'claim provided by small' is the wordplay.
'claim' becomes 'aver' (aver means to state or claim something).
'provided by' is a charade indicator (letters next to each other).
'small' becomes 's' (abbreviation - e.g. clothes size).
'aver' after 's' is 'SAVER'.
(Other definitions for saver that I've seen before include "One no doubt taking interest" , "Raves (anag.)" , "Person with spare cash?" , "Reduced travel fare" , "One budgeting" .)