Swimmer reveals what Ziggy Stardust had? (3,6)
I believe the answer is:
red mullet
I believe this is a double definition.
'swimmer' is the first definition.
(red mullet is a kind of fish)
'what ziggy stardust had?' is the second definition.
'reveals' is the link.
(Other definitions for red mullet that I've seen before include "There's something fishy" , "Brightly coloured food fish" , "Fish -- dull meter (anag)" , "Tasty swimmer" , "one's gathered in net" .)