Altos abandoned low-salt diet and inexplicably lost strength (6)
I believe the answer is:
wilted
'lost strength' is the definition.
('wilt' can be a synonym of 'lose strength')
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for wilted that I've seen before include "Drooped as from heat" , "suffered in the heat" , "(Of a plant) limp" , "Drooped, became limp" , "Lost strength and became limp" .)