Shell-shocked Ottoman commander's the character most often seen in battle (6)
I believe the answer is:
aghast
'shell-shocked' is the definition.
(shell-shocked can mean aghast or astounded)
'ottoman commander's the character most often seen in battle' is the wordplay.
'ottoman commander's' becomes 'agha's' (military title in the Ottoman empire).
'the character most often seen in battle' becomes 'T' (T appears twice in 'battle').
'aghas'+'t'='AGHAST'
(Other definitions for aghast that I've seen before include "Horrified, filled iwth consternation" , "Shocked, dumbfounded" , "Horror-struck" , "Struck with horror" , "Stunned" .)