Support at the front from top officers, before one retreats (9)
I believe the answer is:
brassiere
'support at the front' is the definition.
(item which provides support for breasts)
'top officers before one retreats' is the wordplay.
'top officers' becomes 'brass' (I've seen this in another clue).
'before' becomes 'ere' (poetic term for 'before').
'one' becomes 'i' (Roman numeral).
'retreats' says the letters should be written backwards (I've seen 'retreating' mean this).
'ere'+'i'='erei'
'erei' backwards is 'iere'.
'brass'+'iere'='BRASSIERE'
'from' is the link.
(Other definitions for brassiere that I've seen before include "Female undergarment supporter" , "garment" , "support" .)