Crossword Genius

The value of an Isle on the Thames (5)

Ross

I believe the answer is:

worth

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

'the value' is the definition.
(I've seen this before)

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for worth that I've seen before include "Value (of something)" , "Merit - value" , "Throw (anag.)" .)

I've seen this clue in the Evening Standard.
Want a hint initially instead of a full solution? Install my app