If absolutely necessary, un robinet, ein Hahn, un rubinetto, or üna spina (2,1,5)
I believe the answer is:
at a pinch
'if absolutely necessary' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for at a pinch that I've seen before include "If absolutely necessary" , "In time of difficulty or necessity - nip it" , "In case of necessity" , "in a crisis?" , "in case of emergency" .)