Drink with gritty stuff, hard to get swallowed (6)
I believe the answer is:
Here is my best explanation:
'drink' is the definition.
(shandy is a kind of drink)
'with gritty stuff hard to get swallowed' is the subsidiary indication.
'with gritty stuff' becomes 'sandy'.
'hard' becomes 'h'.
'to get swallowed' is an insertion indicator.
'sandy' enclosing 'h' is 'shandy'.
(Other definitions for shandy that I've seen before include "Drink made of beer and lemonade", "Beer and lemonade drink", "Drink of ale and lemonade 96)", "A misture of ale and lemonade", "Beer/lemonade mixture", "Light beer", "Beer-lemonade mix", "Alcohol", "mixed drink" and "Mixture of beer and lemonade".)