Regular soldiers put November in events book (8)
I believe the answer is:
ordinary
'regular' is the definition.
(thesaurus)
'soldiers put november in events book' is the wordplay.
'soldiers' becomes 'or' (Other Rank).
'put' says to put letters next to each other.
'november' becomes 'n' (phonetic alphabet: alpha, bravo, charlie etc.).
'in' means one lot of letters goes inside another.
'events book' becomes 'diary'.
'n' placed into 'diary' is 'dinary'.
'or'+'dinary'='ORDINARY'
(Other definitions for ordinary that I've seen before include "old bicycle" , "'Commonplace, banal (8)'" , "Customary" , "Commonplace, average" , "charge for arms" .)