Five receive sign of defence (11)
I believe the answer is:
vindication
'defence' is the definition.
(I know that defence can be written as vindication)
'five receive sign' is the wordplay.
I cannot quite see how this works, but
'five' could be 'v' (Roman numeral) and 'v' is found in the answer.
'sign' could be 'indication' (indication is a kind of sign) and 'indication' is found within the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'of' acts as a link.
Can you help me to learn more?
(Other definitions for vindication that I've seen before include "Evidence that frees from blame, criticism etc" , "clearance" , "successful defence" , "acquittal" , "Defence - into da Vinci (anag)" .)