Unemotional son leaves, given refresher course (9)
I believe the answer is:
retrained
'given refresher course' is the definition.
(given training again)
'unemotional son leaves' is the wordplay.
'unemotional' becomes 'restrained' (synonyms).
'son' becomes 's'.
'leaves' indicates named letters should be taken away.
'restrained' with 's' taken out is 'RETRAINED'.
(Other definitions for retrained that I've seen before include "prepared for a new role" , "On losing job, worker may be" , "made fit for new role" .)