Where a washer is always available (2,3)
I believe the answer is:
on tap
'always available' is the definition.
(I've seen this before)
'where a washer' is the wordplay.
I cannot really see how this works, but
'a' is present in the answer.
'washer' could be 'o' (O resembles a metal ring or washer) and 'o' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'is' acts as a link.
Can you help me to learn more?
(Other definitions for on tap that I've seen before include "Ready to be drawn off, say beer" , "Freely available" , "handy" , "Where to find a washer" , "Ready to be drawn off, like beer" .)