Departure, for example, concerning sons (6)
I believe the answer is:
egress
'departure' is the definition.
(I've seen this in another clue)
'example concerning sons' is the wordplay.
'example' becomes 'eg' (short for 'exempli gratia', 'for example' in Latin).
'concerning' becomes 're' (both can mean on a particular topic).
'sons' becomes 'ss' (s is abbreviation for son).
'eg'+'re'+'ss'='EGRESS'
'for' acts as a link.
(Other definitions for egress that I've seen before include "W ay out" , "Means of escape" , "Act of exiting" , "Come out" , "Departure - exit" .)