Humble of French chap to embrace sweetheart (6)
I believe the answer is:
demean
'humble' is the definition.
(demeaning is a kind of humbling)
'of french chap to embrace sweetheart' is the wordplay.
'of french' becomes 'de'.
'chap' becomes 'man' (I've seen this before).
'to embrace' indicates putting letters inside.
'sweetheart' becomes 'e' (the heart/centre of 'sweet').
'man' enclosing 'e' is 'mean'.
'de'+'mean'='DEMEAN'
(Other definitions for demean that I've seen before include "Cause (someone) to suffer loss of dignity" , "Stoop" , "Humble" , "Reduce in worth" , "Cause to lose respect" .)