Most revealing that top surgeon stole ballpoint from harassed obstetrician (9)

'most revealing' is the definition.
Both the answer and definition are superlative adjectives. Maybe there's a link between them I don't understand?

'top surgeon stole ballpoint from harassed obstetrician' is the wordplay.
I cannot really see how this works, but
'from' could be 'e' (I've seen this in other clues) and 'e' is found within the answer.
'top' could be 'ist' (resembles 1st) and 'ist' is found within the remaining letters.
The remaining letters 'scant' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...

'that' is the link.

Can you help me to learn more?