By the sound of it, a Channel Island providing oversea refuge in 1746 (4)
I believe the answer is:
skye
'a channel island providing oversea refuge in 1746' is the definition.
I can't tell whether this defines the answer.
'by the sound of it' is the wordplay.
'by' means one lot of letters go next to another.
'the sound of' becomes 'sky' (I can't explain this - if you can you should give a lot more credence to this answer).
'it' becomes 'e' ('e' can mean 'electronic' which is similar to 'IT').
'sky' next to 'e' is 'SKYE'.
Can you help me to learn more?
(Other definitions for skye that I've seen before include "Where Bonnie Prince Charlie fled after his defeat at Culloden" , "Inner Hebridean isle" , "Portree's isle" , "Destination of a princely boat trip" , "Island in a boat song about Flora MacDonald and Bonnie Prince Charlie" .)