Rail, I've learnt, challenged journeying through the skies (7,6)

'skies' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.

'rail i've learnt challenged journeying through the' is the wordplay.
I cannot quite understand how this works, but
an anagram of 'rail' is 'airl' which is located in the answer.
'through' could be 'in' and 'in' is found within the answer.
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?