Campaigner badly scarred around Ulm initially (8)
I believe the answer is:
crusader
'campaigner' is the definition.
(I've seen this before)
'badly scarred around ulm initially' is the wordplay.
'badly' indicates anagramming the letters.
'around' is an insertion indicator.
'initially' indicates taking the first letters.
The first letter of 'ulm' is 'u'.
'scarred' anagrammed gives 'crsader'.
'crsader' going around 'u' is 'CRUSADER'.
(Other definitions for crusader that I've seen before include "RA cursed (anag) - one fighting for a cause" , "For example, Richard I" , "One campaigning vigorously" , "Medieval expeditionary" , "religious zealot" .)