Continues holding back group of soldiers (4)
I believe the answer is:
unit
'group of soldiers' is the definition.
(unit can mean a group of soldiers)
'continues holding back' is the wordplay.
'holding' indicates a hidden word.
'back' says the letters should be written backwards.
'tinu' is hidden within 'continues'.
'tinu' reversed gives 'UNIT'.
(Other definitions for unit that I've seen before include "Some fighting men" , "A single self-contained item" , "Individual thing, single and complete" , "Standard for measuring" , "1 entity" .)