Part of reign is pale reminder about failing again? (9)

'failing again?' is the definition.
The definition and answer can be both related to change as well as being present participle verbs.
Perhaps there's an association between them I don't understand?

'part of reign is pale reminder about' is the wordplay.
'part of' says the answer is hidden in the clue.
'about' says the letters should be written in reverse.
'gnispaler' is hidden in the letters of 'reign is pale reminder'.
'gnispaler' in reverse letter order is 'RELAPSING'.

Can you help me to learn more?