Is this clue like an Alka-Seltzer? (7)
I believe the answer is:
soluble
I believe this is a double definition.
'is this clue' is the first definition.
(a clue is soluble - it can be solved)
'like an alka-seltzer?' is the second definition.
(Alka-Seltzers are soluble tablets)
(Other definitions for soluble that I've seen before include "Lobules (anag)" , "Like this T 2, one hopes" , "Capable of being solved or dissolved" , "Aspirin (or problems) may be" , "Capable of being solved (in water?)" .)