Want son to entertain the French? That’s uncalled-for (8)
I believe the answer is:
needless
'uncalled-for' is the definition.
(I've seen this before)
'want son to entertain the french?' is the wordplay.
'want' becomes 'need' ('need' can be a synonym of 'want'**).
'son' becomes 's'.
'to entertain' means one lot of letters goes inside another.
'the french?' becomes 'les' (les is the in french).
'need'+'s'='needs'
'needs' going around 'les' is 'NEEDLESS'.
'that's' is the link.
(Other definitions for needless that I've seen before include "uncalled for" , "Otiose" , "Unneccessary and unwarranted" , "Surplus to requirements" , "Without reason" .)