Examine said rule first to get ticket that's valid later (4,5)
I believe the answer is:
rain check
'get ticket that's valid later' is the definition.
I can't tell whether this defines the answer.
'examine said rule first' is the wordplay.
'examine' becomes 'check' (checking is a kind of examining).
'said rule' becomes 'rain' (I can't justify this - if you can you should believe this answer much more).
'first' means one lot of letters go next to another.
'check' after 'rain' is 'RAIN CHECK'.
'to' is the link.
Can you help me to learn more?
(Other definitions for rain check that I've seen before include "Ticket issued for later use if an event is delayed through weather (US)" , "Deferral of acceptance - testing weather?" , "Postponement" .)