A number to remember (3)
I believe the answer is:
pin
This clue could be a double definition.
'a number' is the first definition.
(I've seen this before)
'remember' is the second definition.
Although both the answer and definition are verbs in their base form, I can't see how they can define each other.
'to' is the link.
Can you help me to learn more?
(Other definitions for pin that I've seen before include "Number allocated for electronic transactions" , "Fasten; a security code" , "Fixing device" , "Secure" , "Tack; fasten" .)