A blow for progress! (8)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
tailwind
But I can't explain it at all! Could you help me understand?
(Other definitions for tailwind that I've seen before include "Boost for one running" , "Favourable air current" , "Blow to back" , "It increases one's (ground)speed" .)