Coming from an embittered source? (4)
I believe the answer is:
sour
'embittered source?' is the definition.
'sour' can be an answer for 'embittered' (I've seen this before). I am unsure of the 'source?' bit.
'coming from an' is the wordplay.
I cannot quite see how this works, but
'from' could be 'o' (I've seen this in other clues) and 'o' is located in the answer.
The remaining letters 'sur' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for sour that I've seen before include "Tasting sharp like stale milk" , "Embittered" , "Tart, acidic" , "Sharp- or tart-tasting" , "Disparagement of something one can't have oneself" .)