Single-minded cadet died in explosion (9)
I believe the answer is:
dedicated
'single-minded' is the definition.
(I've seen this before)
'cadet died in explosion' is the wordplay.
'in explosion' is an anagram indicator (I've seen this in other clues).
'cadet'+'died'='cadetdied'
'cadetdied' is an anagram of 'DEDICATED'.
(Other definitions for dedicated that I've seen before include "Customised" , "Hard working" , "Committed" , "Devoted to a particular cause or purpose" , "Devoted to a task or purpose" .)