Pedant tense? No, it's I, corrected (13)
I believe the answer is:
perfectionist
'pedant' is the definition.
(thesaurus)
'tense? no it's i corrected' is the wordplay.
'tense?' becomes 'perfect' (perfect is a kind of tense**).
'corrected' indicates anagramming the letters.
'no'+'its'+'i'='noitsi'
'noitsi' is an anagram of 'ionist'.
'perfect'+'ionist'='PERFECTIONIST'
(Other definitions for perfectionist that I've seen before include "One striving for an ideal standard" , "Striver for the ideal" , "One seeking the ideal" , "One aiming for the best" , "I expect the best" .)