Fashion in dress at start of Wimbledon showing glitz (10)
I believe the answer is:
tawdriness
'glitz' is the definition.
('tawdriness' can be a synonym of 'glitz')
'fashion in dress at start of wimbledon' is the wordplay.
'fashion' indicates anagramming the letters.
'start of' suggests taking the first letters.
The initial letter of 'wimbledon' is 'w'.
'in'+'dress'+'at'+'w'='indressatw'
'indressatw' with letters rearranged gives 'TAWDRINESS'.
'showing' acts as a link.
(Other definitions for tawdriness that I've seen before include "tacky" , "Tastelessness and worthlessness" , "Shabby, poor quality" , "Cheap and showy quality" .)