Leave boy enclosing the third of four initial letters (7)
I believe the answer is:
abscond
'leave' is the definition.
(I know that abscond is a type of flee)
'boy enclosing the third of four initial letters' is the wordplay.
I cannot really understand how this works, but
'boy' could be 'con' and 'con' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for abscond that I've seen before include "scarper" , "cut and run" , "Escape, flit" , "Leave to escape arrest" , "make quick getaway" .)