Tall tale is so like a big pill! (4,2,7)
I believe the answer is:
hard to swallow
'tall' is the definition.
(I've seen this in another clue)
'tale is so like a big pill' is the wordplay.
I cannot quite understand how this works, but
'a' is within the answer.
'big' could be 'os' and 'os' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for hard to swallow that I've seen before include "Tall" , "beyond belief" , "laryngitis sufferer finds it so?" , "Difficult to believe" , "Dry cream crackers are" .)