Way out Frenchman rejected son (6)
I believe the answer is:
egress
'way' is the definition.
(thesaurus)
'out frenchman rejected son' is the wordplay.
'out' is an insertion indicator.
'frenchman' becomes 'serge' (I've seen this before).
'rejected' is a reversal indicator.
'son' becomes 's' (genealogical abbreviation for son).
'serge' written backwards gives 'egres'.
'egres' going around 's' is 'EGRESS'.
(Other definitions for egress that I've seen before include "Way to go out" , "Way out of serges" , "means of leaving" , "Come out" , "Emergence, coming out" .)