Animal in Italian river good for source of biodiversity (5)
I believe the answer is:
tiger
'animal' is the definition.
(I've seen this before)
'italian river good for source of biodiversity' is the wordplay.
I cannot really see how this works, but
'italian' could be 'i' (abbreviation for Italian) and 'i' is present in the answer.
'river' could be 'r' and 'r' is located in the answer.
'good' could be 'g' (abbreviation) and 'g' is found within the answer.
The remaining letters 'te' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'in' acts as a link.
(Other definitions for tiger that I've seen before include "dynamic economy" , "Fierce Bengal beast" , "Formidable competitor" , "Large feline of the forests" , "Striped animal poetically burning bright" .)