A bodybuilder’s heavenly body (8)

I believe the answer is:

asteroid

'heavenly body?' is the definition.
(I know that asteroid is a type of minor planet)

'a bodybuilder's' is the wordplay.
'bodybuilder' becomes 'steroid' (as in the type of drug).
'a'+'steroid'='ASTEROID'

(Other definitions for asteroid that I've seen before include "Piece of rock that moves around the heavens" , "could be dangerous for astronauts" , "Small heavenly body" , "Rocky body in orbit" , "way-out rock" .)

I've seen this clue in The Telegraph and The Sunday Times.

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