One in 52 is frail, say (4)
I believe the answer is:
week
'one in 52' is the definition.
I can't judge whether this defines the answer.
'frail say' is the wordplay.
'frail' becomes 'weak' (similar in meaning).
'say' shows a homophone (sound like).
'weak' is a homophone of 'WEEK'.
'is' is the link.
Can you help me to learn more?
(Other definitions for week that I've seen before include "Period of time; sounds like feeble" , "Seven days" , "Part of the year" , "Calendar period" , "A long time in politics?" .)