Unofficially failing to beat previous best (3,3,6)
I believe the answer is:
off the record
'unofficially' is the definition.
(I've seen this before)
'failing to beat previous best' is the wordplay.
I cannot quite understand how this works, but
'best' could be 'record' (similar in meaning) and 'record' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for off the record that I've seen before include "Not for quotation" , "not intended for release?" , "Unofficial (briefing)" , "unprintable" , "Source not to be cited" .)