Marched from military store, rounding men up (7)
I believe the answer is:
trooped
'marched' is the definition.
(trooping is a kind of marching)
'military store rounding men up' is the wordplay.
'military store' becomes 'depot' (depot can mean a store or warehouse. I am not sure about the 'military' bit.).
'rounding' indicates putting letters inside.
'men' becomes 'OR' (military abbreviation for Other Ranks).
'up' says the letters should be written backwards (in down clue: letters go upwards).
'depot' going around 'or' is 'depoort'.
'depoort' in reverse letter order is 'TROOPED'.
'from' acts as a link.
Can you help me to learn more?
(Other definitions for trooped that I've seen before include "Paraded" , "Went as a body" , "Moved in a body, like soldiers with colours" , "Marched in a procession" .)