Staunch advocate for science, technology etc (4)
I believe the answer is:
stem
'staunch' is the definition.
(I know that staunch can be written as stem)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for stem that I've seen before include "Central upright part of flower or drinking glass" , "supporter of flag, for example" , "Restrain - staunch - supporter" , "Thin vertical part of glass or plant" , "Shoot; arrest" .)