Completely destroy way of escape, by the sound of it (4,3)
I believe the answer is:
root out
'completely destroy' is the definition.
'root out' can be an answer for 'destroy' (thesaurus). I'm not sure about the 'completely' bit.
'way of escape by the sound of it' is the wordplay.
I cannot quite see how this works, but
'way' could be 'r' (abbreviation for right) and 'r' is found in the answer.
'of' could be 'o' and 'o' is found within the answer.
'escape' could be 'out' (as in giving someone an out) and 'out' is located in the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found in the answer.
A single letter 'o' remains 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 root out that I've seen before include "Destroy completely" , "Extirpate, find and destroy" , "Extirpate, eradicate" , "Completely remove" , "Get rid or, extirpate" .)