Bars and courts ridiculously packed in summer time in UK (9)
I believe the answer is:
obstructs
'bars' is the definition.
'courts ridiculously packed in summer time in uk' is the wordplay.
'ridiculously' indicates an anagram.
'packed in' is an insertion indicator (I've seen this in other clues).
'summer time in uk' becomes 'bst' (British Summer Time).
'courts' with letters rearranged gives 'oructs'.
'oructs' placed around 'bst' is 'OBSTRUCTS'.
'and' acts as a link.
(Other definitions for obstructs that I've seen before include "Prevents or hinders passage" , "Blocks" .)