Can it turn the tide of obesity? (4)
I believe the answer is:
diet
'can it' is the definition.
I can't tell whether this defines the answer.
'turn the tide of obesity?' is the wordplay.
'turn' becomes 'die' (dying is a kind of turning).
'the tide of obesity?' becomes 't' (I can't justify this - if you can you should give a lot more credence to this answer).
'die'+'t'='DIET'
Can you help me to learn more?
(Other definitions for diet that I've seen before include "Special food regime" , "Slimmer's regimen" , "control weight" , "Food - parliament" , "The kinds of food one eats" .)