Supermarket taking American graduate instead of European - it can be hard to swallow (7)

'swallow' is the definition.
The answer and definition can be both things that one consumes for nourishment as well as being singular nouns.
Perhaps you can see an association between them that I don't see?

'supermarket taking american graduate instead of european it can be hard' is the wordplay.
I cannot quite see how this works, but
'american' could be 'a' (common abbreviation - e.g. in organisation names) and 'a' is found within the answer.
'graduate' could be 'ba' (someone with a Bachelor of Arts degree) and 'ba' is found within the answer.
'of' could be 'o' and 'o' is located in the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is located in the answer.
This may be the basis of the clue (or it may be nonsense).

'to' acts as a link.

Can you help me to learn more?