Fury after avenue seen as mediocre (7)
I believe the answer is:
average
'mediocre' is the definition.
(I know that mediocre can be written as average)
'fury after avenue' is the wordplay.
'fury' becomes 'rage' (synonyms).
'after' says to put letters next to each other.
'avenue' becomes 'ave'.
'rage' put after 'ave' is 'AVERAGE'.
'seen as' acts as a link.
(Other definitions for average that I've seen before include "Mean - norm" , "It may be mean" , "Mean, so-so" , "Arithmetically ordinary?" , "Usual - mediocre - mean" .)