Show an interest in the bar code? (4)
I believe the answer is:
scan
'interest in the bar code?' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'show an' is the wordplay.
'show' becomes 'sc' (I can't justify this - if you can you should give a lot more credence to this answer).
'sc'+'an'='SCAN'
Can you help me to learn more?
(Other definitions for scan that I've seen before include "Convert (a document) to a digital form" , "Examine (to transmit)" , "Take a quick look" , "Inspect" , "Skim; examine" .)