Tiresome fashion dies out (7)
I believe the answer is:
tedious
'tiresome' is the definition.
(I know that tiresome can be written as tedious)
'fashion dies out' is the wordplay.
'fashion' indicates an anagram.
'dies'+'out'='diesout'
'diesout' is an anagram of 'TEDIOUS'.
(Other definitions for tedious that I've seen before include "drab" , "Dull as ditchwater" , "Long, slow, dull" , "Outside (anag.)" , "not exciting" .)