When licked it may go into a corner (7,5)
I believe the answer is:
postage stamp
'corner' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'when licked it may go into a' is the wordplay.
I cannot really see how this works, but
'when' could be 'e' (I've seen this in other clues) and 'e' is found within the answer.
'it' could be 'tag' (playground catching game) and 'tag' is located in the answer.
'a' could be 'amp' (A is the symbol for the amp or ampere) and 'amp' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for postage stamp that I've seen before include "Token stuck on a letter -- ATM stoppages (anag)" , "Label stuck on envelope" , "Corresponding need" , "Indication of payment for sending letter" , "Mail sticker" .)