Oversight of old girl no one recalled (8)
I believe the answer is:
omission
'oversight' is the definition.
(omission is a kind of oversight)
'old girl no one recalled' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'girl' becomes 'miss' (I've seen this before**).
'one' becomes 'i' (Roman numeral).
'recalled' is a reversal indicator.
'no'+'i'='noi'
'noi' in reverse letter order is 'ion'.
'o'+'miss'+'ion'='OMISSION'
'of' is the link.
(Other definitions for omission that I've seen before include "task not done" , "Failure to include" , "Negligence" , "A thing left out" , "Something left out or forgotten" .)