Claim, old, gets agreed (6)
I believe the answer is:
righto
'agreed' is the definition.
(I've seen this before)
'claim old' is the wordplay.
'claim' becomes 'right' (I've seen this before).
'old' becomes 'o' (abbreviation as in OT - Old Testament).
'right'+'o'='RIGHTO'
'gets' acts as a link.
(Other definitions for righto that I've seen before include "fine" , "OK" , "Correct" , "Okey doke" , "Okey-dokey" .)