Wodehouse character in court, unsmiling mostly (7)
I believe the answer is:
wooster
'wodehouse character' is the definition.
(I've seen this before)
'court unsmiling mostly' is the wordplay.
'court' becomes 'woo' ('woo' can be a synonym of 'court').
'unsmiling' becomes 'stern' (I've seen this before).
'mostly' means to remove the last letter.
'stern' with its last letter taken away is 'ster'.
'woo'+'ster'='WOOSTER'
'in' is the link.
(Other definitions for wooster that I've seen before include "Vacuous toff" , "Jeeves' employer" , "Drone" , "English gentlemen" , "Wodehouse character" .)