Band provides hard support for special forces (4)
I believe the answer is:
sash
'band' is the definition.
(sash is a kind of band)
'hard support for special forces' is the wordplay.
'hard' becomes 'h' (abbreviation used in pencil classifications).
'support for' says to put letters next to each other.
'special forces' becomes 'sas' (I've seen this in other clues).
'h' put after 'sas' is 'SASH'.
'provides' is the link.
(Other definitions for sash that I've seen before include "type of cord?" , "Window frame; cloth strip (worn over shoulder)" , "Decoration for the twelfth" , "Brown bread for waist or shoulder" , "Broad band, the one me father wore?" .)