Went fast - yet at disheartening speed? (4)
I believe the answer is:
sped
'went fast' is the definition.
(I've seen this before)
'disheartening speed?' is the wordplay.
'disheartening' says to hollow out the word (remove centre letters).
'speed' with its centre removed is 'SPED'.
'yet at' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for sped that I've seen before include "got a move on" , "Raced, hurried" , "Went fast" , "Made haste" , "Moved fast" .)