Couple prepare for impact (5)
I believe the answer is:
brace
I believe this clue is a double definition.
'couple' is the first definition.
(brace can mean a pair of something)
'prepare for impact' is the second definition.
(I've seen this before)
(Other definitions for brace that I've seen before include "Tighten, strengthen" , "Support or hold steady" , "Support - couple" , "Pair; hand drill" , "Stiffen; pair" .)