Irregular criteria one removed, tentatively (7)
I believe the answer is:
erratic
'irregular' is the definition.
(I've seen this before)
'criteria one removed tentatively' is the wordplay.
'one' becomes 'i' (Roman numeral).
'removed' indicates named letters should be taken away.
'tentatively' indicates anagramming the letters.
'criteria' with 'i' taken away is 'crteria'.
'crteria' is an anagram of 'ERRATIC'.
(Other definitions for erratic that I've seen before include "Random, unreliable" , "Not regular in pattern" , "Volatile" , "Inconsistent, shifting" , "Fluctuating" .)