Elite soldiers, hard band (4)
I believe the answer is:
sash
'band' is the definition.
(a band of material)
'elite soldiers hard' is the wordplay.
'elite soldiers' becomes 'sas' (Special Air Service).
'hard' becomes 'h' (abbreviation used in pencil classifications).
'sas'+'h'='SASH'
(Other definitions for sash that I've seen before include "Framework holding window panes" , "Band worn over shoulder or round waist" , "Cummerbund" , "Broad band, the one me father wore?" , "Brown bread for waist or shoulder" .)