Function of a court (3)
I believe the answer is:
act
'function' is the definition.
(I've seen this before)
'a court' is the wordplay.
'court' becomes 'ct'.
'a'+'ct'='ACT'
'of' acts as a link.
(Other definitions for act that I've seen before include "Something done" , "turn" , "Bill successfully prosecuted" , "Major division of play" , "Aussie parliamentarians exert influence here?" .)