Knowledge about island and river (5)
I believe the answer is:
loire
'river' is the definition.
(I know that Loire is a river)
'knowledge about island' is the wordplay.
I cannot really understand how this works, but
'about' could be 're' (regarding) and 're' is found within the answer.
'island' could be 'i' (geographical abbreviation) and 'i' is found within the answer.
The remaining letters 'lo' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'and' is the link.
Can you help me to learn more?
(Other definitions for loire that I've seen before include "department in France" , "French runner" , "River flowing through Tours and Nantes" , "Longest French river" , "flower abroad" .)