Alleged decimal system (7)
I believe the answer is:
claimed
'alleged' is the definition.
(I've seen this before)
'decimal system' is the wordplay.
'decimal' can be anagrammed to 'CLAIMED'.
Though, I am not clear how this is indicated.
Can you help me to learn more?
(Other definitions for claimed that I've seen before include "Asserted right to or interest in" , "Declared" , "Asserted one's right to" , "Asserted, contended" , "Called for" .)