Labels on trendy southern firms' top products (9)

'labels on trendy southern firms' top products' is the definition.
The answer and definition can be both man-made objects as well as being plural nouns.
Maybe you can see a link between them that I don't see?

'on trendy southern firms' top products' is the wordplay.
'on' says to put letters next to each other.
'trendy' becomes 'hip' (both can mean fashionable).
'southern' becomes 's' (abbreviation).
'firms' top products' becomes 'flags' (I can't explain this - if you can you should give a lot more credence to this answer).
'hip'+'s'='hips'
'hips' put after 'flags' is 'FLAGSHIPS'.

Can you help me to learn more?