Couple finally had to be supported (6)
I believe the answer is:
braced
'to be supported' is the definition.
('braced' can be similar in meaning to 'supported')
'couple finally' is the wordplay.
'couple' becomes 'brace' ('brace' can be a synonym of 'couple').
'finally' becomes 'd' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'brace'+'d'='BRACED'
'had' acts as a link.
Can you help me to learn more?
(Other definitions for braced that I've seen before include "Stiff" , "Ready for action" , "Steadied against a blow or shock" , "Supported, gave firmness to" , "Ready for impact - wearing trouser straps" .)