Horrified Turkish commander stumped (6)
I believe the answer is:
aghast
'horrified' is the definition.
(thesaurus)
'turkish commander stumped' is the wordplay.
'turkish commander' becomes 'agha' (I've seen this before).
'stumped' becomes 'st' (I've seen this in other clues).
'agha'+'st'='AGHAST'
(Other definitions for aghast that I've seen before include "Very unhappy" , "Thunderstruck" , "Appalled, shocked" , "Stupefied with horrer" , "Deeply dismayed" .)