An enhancing drug for heavenly body (8)
I believe the answer is:
asteroid
'heavenly body' is the definition.
(asteroid is a kind of heavenly body)
'an enhancing drug' is the wordplay.
'an enhancing' becomes 'a' (I can't explain this - if you can you should believe this answer much more).
'drug' becomes 'steroid' (I've seen this before).
'a'+'steroid'='ASTEROID'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for asteroid that I've seen before include "Small celestial body composed of rock and metal" , "Piece of rock that moves around the heavens" , "Bit of rock that moves around the heavens" , "could be dangerous for astronauts" , "Bits of rock that move around the heavens" .)