Heavenly body in need of a man-made hormone (7)
I believe the answer is:
steroid
'man-made hormone' is the definition.
'steroid' can be an answer for 'hormone' (steroid hormone is a kind of hormone). I'm unsure of the 'man-made' bit.
'heavenly body in need of a' is the wordplay.
'heavenly body' becomes 'asteroid' (asteroid is a kind of heavenly body).
'in need of' indicates named letters should be taken away.
'asteroid' with 'a' taken away is 'STEROID'.
Can you help me to learn more?
(Other definitions for steroid that I've seen before include "Organic compound" , "Compound used as drug or performance enhancer" , "Hormone perhaps" , "Body-building drug" , "Type of hormone" .)