Explorer abandoning vehicle ahead of new group of fighters (6)
I believe the answer is:
column
'group of fighters' is the definition.
(strategic arrangement of soldiers)
'explorer abandoning vehicle ahead of new' is the wordplay.
'explorer' becomes 'columbus' (Christopher Columbus).
'abandoning' indicates named letters should be taken away.
'vehicle' becomes 'bus' (bus is a kind of vehicle).
'ahead of' says to put letters next to each other (I've seen this in other clues).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'columbus' with 'bus' removed is 'colum'.
'colum'+'n'='COLUMN'
(Other definitions for column that I've seen before include "Nelson's supporter?" , "Pillar - contribution to newspaper" , "Pillar - newspaper slot" , "Tower" , "Convulsive muscular contraction" .)