Vast new semi accommodating soldiers (7)
I believe the answer is:
immense
'vast' is the definition.
(thesaurus)
'new semi accommodating soldiers' is the wordplay.
'new' indicates anagramming the letters.
'accommodating' means one lot of letters goes inside another.
'soldiers' becomes 'men' (I've seen this before).
'semi' is an anagram of 'imse'.
'imse' going around 'men' is 'IMMENSE'.
(Other definitions for immense that I've seen before include "'Vast, colossal (7)'" , "Mammoth" , "'Gigantic, extensive (7)'" , "Very good" , "Huge, really great" .)