Thus repeatedly mediocre (2-2)
I believe the answer is:
so-so
'mediocre' is the definition.
(thesaurus)
'thus repeatedly' is the wordplay.
'thus' becomes 'so' (synonyms).
'repeatedly' says to double the letters.
'so' duplicated is 'SO-SO'.
(Other definitions for so-so that I've seen before include "just about adequate" , "Tolerable, indifferent" , "Neither good nor bad" , "Mediocre" , "Rather middling" .)