Fluently available (2,3)
I believe the answer is:
on tap
'available' is the definition.
(similar in meaning)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for on tap that I've seen before include "Ready to be drawn off, like beer" , "where C or H is seen?" , "kept in a cask" , "Of liquid gas, ready to be drawn off" , "Constantly available like beer from keg" .)