Secretary upset friend in shock (5)
I believe the answer is:
appal
'shock' is the definition.
(synonyms)
'secretary upset friend' is the wordplay.
'secretary' becomes 'PA' (abbreviation for personal assistant).
'upset' shows that the letters should be reversed in order.
'friend' becomes 'pal' (pal can mean a friend).
'pa' written backwards gives 'ap'.
'ap'+'pal'='APPAL'
'in' acts as a link.
(Other definitions for appal that I've seen before include "Shock, horrify" , "Cause to be unpleasantly surprised" , "Disgust" , "Greatly horrify" , "Petrify" .)