Wearing retro skirt as part of retro racket (7)
I believe the answer is:
erosion
'wearing' is the definition.
(I know that wearing can be written as erosion)
'retro skirt as part of retro racket' is the wordplay.
'skirt' suggests removing the centre (skirt can mean the edge or outside of something).
'as part of' means one lot of letters goes inside another.
'retro' shows that the letters should be reversed in order (retro is Latin for 'backwards').
'racket' becomes 'noise' (racket can mean a loud noise).
'retro' with its centre taken out is 'ro'.
'noise' in reverse letter order is 'esion'.
'ro' placed inside 'esion' is 'EROSION'.
(Other definitions for erosion that I've seen before include "Deterioration of soil etc" , "Gradual decline" , "dying away" , "Mechanical process of wearing something down" , "Action of wearing away" .)