Could be spent in Tokyo, for instance (3)
I believe the answer is:
yen
'instance' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'could be spent in tokyo' is the wordplay.
'could' becomes 'may' (I've seen this before).
'be' becomes 'am'.
'spent in' suggests deleting specific letters (to spend can mean to waste or give away).
'tokyo' becomes 'en' (I can't explain this - if you can you should believe this answer much more).
'may' with 'am' removed is 'y'.
'y'+'en'='YEN'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for yen that I've seen before include "money in Tokyo" , "foreign currency" , "Have a longing for Japanese money?" , "change in East" , "Longing for a currency unit" .)