Roast tuna salad for Major Tom? (9)
I believe the answer is:
astronaut
'major tom?' is the definition.
(Major Tom, astronaut in David Bowie songs)
'roast tuna salad' is the wordplay.
'salad' indicates anagramming the letters (salad can refer to a mixture).
'roast'+'tuna'='roasttuna'
'roasttuna' is an anagram of 'ASTRONAUT'.
'for' acts as a link.
(Other definitions for astronaut that I've seen before include "One travelling in space" , "Skier" , "Armstrong or Sharman, say" , "High-flyer" , "high flier" .)