Supporting British in competition (7)
I believe the answer is:
bracing
'supporting' is the definition.
(bracing is a kind of supporting)
'british in competition' is the wordplay.
'british' becomes 'br'.
'in competition' becomes 'acing' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'br'+'acing'='BRACING'
Can you help me to learn more?
(Other definitions for bracing that I've seen before include "Supporting" , "Strengthening; fresh" , "Fresh and invigorating" , "brisk" , "Imparting vitality" .)