A row following the French introduction (4-2)
I believe the answer is:
lead-in
'introduction' is the definition.
(I've seen this before)
'a row following the french' is the subsidiary indication.
'row' becomes 'din' (both can mean a loud disturbance).
'following' says to put letters next to each other.
'the french' becomes 'le'.
'a'+'din'='adin'
'adin' put after 'le' is 'leadin'.
(Other definitions for lead-in that I've seen before include "Introduction, preamble" , "Introduction to subject" , "Introductory passage" .)