Old coin, one lying in the sun? (6)
I believe the answer is:
I believe this clue is a double definition.
'old coin' is the first definition.
(historical sixpence coin)
'one lying in the sun?' is the second definition.
(someone trying to get a sun tan)
(Other definitions for tanner that I've seen before include "Curer of hides, maker of leather" , "Hide worker; old coin" , "one getting bronzed?" , "One might catch the sun" , "Pre-decimal sixpenny piece" .)