Flower provided by online store (6)
I believe the answer is:
amazon
'flower' is the definition.
(Amazon River is an example)
'online store' is the wordplay.
I cannot really see how this works, but
'online' could be 'on' (similar in meaning) and 'on' is located in the answer.
This explanation may well be incorrect...
'provided by' acts as a link.
Can you help me to learn more?
(Other definitions for amazon that I've seen before include "Great river of S America, or a tough woman" , "tropical fish swimming here" , "Mighty river of S America, or tough woman" , "One of a mythic nation of women warriors" , "banker" .)