Being fit and well led on to a high, perhaps (2,4,6)
I believe the answer is:
in good health
'being fit' is the definition.
(I've seen this before)
'led on to a high perhaps' is the wordplay.
'perhaps' indicates an anagram.
'led'+'on'+'to'+'a'+'high'='ledontoahigh'
'ledontoahigh' with letters rearranged gives 'IN GOOD HEALTH'.
'and well' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Another definition for in good health that I've seen is " Fit".)