Machine able to provide endless health? (5)
I believe the answer is:
lathe
'machine' is the definition.
(I've seen this before)
'provide endless health?' is the wordplay.
'provide' becomes 'ply' ('ply' can be a synonym of 'provide').
'endless' indicates the central letters.
'health?' becomes 'athe' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
The central letter of 'ply' is 'l'.
'l'+'athe'='LATHE'
'able to' is the link.
This may not be correct. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for lathe that I've seen before include "Machine for turning and shaping wood etc" , "Turner's tool" , "This is turned out" , "Machine for cutting, drilling or polishing" , "Turner's machine" .)