The French head of department with plate behaving like some young men (7)
I believe the answer is:
laddish
'behaving like some young men' is the definition.
I can't tell whether this defines the answer.
'the french head of department with plate' is the wordplay.
'the french' becomes 'la' (one of the French words for 'the').
'head of' indicates taking the first letters.
'with' means one lot of letters go next to another.
'plate' becomes 'dish' (type of plate).
The first letter of 'department' is 'd'.
'la'+'d'+'dish'='LADDISH'
Can you help me to learn more?
(Other definitions for laddish that I've seen before include "Given to immature and aggressive behaviour" , "How like a boy" , "Boisterously macho" , "Macho and immature" , "Like a young man" .)