Source of hot water and an internal treatment for eyes (6)
I believe the answer is:
geyser
'source of hot water' is the definition.
The answer and definition can be both natural objects as well as being singular nouns.
Perhaps you can see an association between them that I don't see?
'an internal treatment for eyes' is the wordplay.
I cannot quite understand how this works, but
an anagram of 'eyes' is 'eyse' which is present in the answer.
This may be the basis of clue (or it may be nonsense).
'and' is the link.
Can you help me to learn more?
(Other definitions for geyser that I've seen before include "Gas-fired water heater" , "It blows off steam" , "Intermittent hot spring" , "Steaming spring" , "Spring spouting steam and hot water" .)