Engineer Bob married NCO in artillery (10)
I believe the answer is:
bombardier
'nco in artillery' is the definition.
(type of non-commissioned officer)
'engineer bob married' is the wordplay.
'engineer' indicates anagramming the letters.
'bob'+'married'='bobmarried'
'bobmarried' anagrammed gives 'BOMBARDIER'.
(Other definitions for bombardier that I've seen before include "NCO" , "Artillery rank" , "Royal Artillery soldier" .)