They can hardly be flammable (5)

I believe the answer is:

ashes

I'm a little stuck... Click here to teach me more about this clue!

'they' is the definition.
Both the definition and answer are plural nouns.
Perhaps you can see a link between them that I can't see?

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for ashes that I've seen before include "Test-match trophy" , "Remains of anything burnt" , "Former Wimbledon champion's" , "International competition" , "Powders remaining after fire" .)

I've seen this clue in the Evening Standard.

Want a hint initially instead of a full solution? Install my app