Drink, uninteresting, altered internally with spice (7)
I believe the answer is:
gingery
'drink uninteresting altered' is the definition.
I can't tell whether this definition defines the answer.
'internally with spice' is the wordplay.
'internally' becomes 'y' (I can't explain this - if you can you should give a lot more credence to this answer).
'with' means one lot of letters go next to another.
'spice' becomes 'ginger' (ginger is a spice).
'y' after 'ginger' is 'GINGERY'.
Can you help me to learn more?
(Another definition for gingery that I've seen is " what's hot and spicy".)