Island within French sea board having value (9)

'having value' is the definition.
I can't judge whether this definition defines the answer.

'island within french sea board' is the wordplay.
I cannot quite understand how this works, but
'island' could be 'i' (geographical abbreviation) and 'i' is found within the answer.
'sea' could be 'mer' (I have seen 'French sea ' mean 'mer' so perhaps 'sea' could also mean 'mer') and 'mer' is located in the answer.
'board' could be 'table' (both can mean food) and 'table' is found in the answer.
No letters remain.
This explanation may well be incorrect...

Can you help me to learn more?