Soldier in terrible danger, one with little sign of hesitation (9)
I believe the answer is:
grenadier
'soldier' is the definition.
(historical term for a grenade-carrying soldier)
'terrible danger one with little sign of hesitation' is the wordplay.
'terrible' is an anagram indicator.
'one' becomes 'I' (Roman numeral).
'with' says to put letters next to each other.
'little sign of hesitation' becomes 'er' (short exclamation indicating hesitation).
'danger' anagrammed gives 'grenad'.
'grenad'+'i'+'er'='GRENADIER'
'in' acts as a link.
(Other definitions for grenadier that I've seen before include "Infantryman - in red gear (anag)" , "historical bomber" , "Soldier - in red gear (anag)" , "African flier" , "Soldier; fish; bird" .)