Score which is doubled in cricket (6)
I believe the answer is:
twenty
This clue is a double definition.
'score' is the first definition.
(synonyms)
'doubled in cricket' is the second definition.
(T20 or twenty20 cricket - short cricket match)
'which is' is the link.
(Other definitions for twenty that I've seen before include "Cardinal" , "No longer a teenager" , "Hundredweights to a ton" , "previous clue?" , "made by Q on a light blue square" .)