Gosh, what a start it gave Dobbin! (3)
I believe the answer is:
gee
'gosh' is the definition.
(I've seen this before)
'what a start it gave dobbin' is the wordplay.
I cannot really see how this works, but
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found within the answer.
The remaining letters 'ge' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for gee that I've seen before include "Exclamation of surprise" , "Golly" , "G" , "move faster" , "crumbs" .)