Poor formality, I aver, involves one showing this? (4-11)

I believe the answer is:

over-familiarity

'poor formality i aver involves one showing this?' is the definition.
(cryptic definition)

'poor formality i aver involves one' is the wordplay.
'poor' indicates anagramming the letters.
'involves' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'formality'+'i'+'aver'='formalityiaver'
'formalityiaver' with letters rearranged gives 'overfamliarity'.
'overfamliarity' enclosing 'i' is 'OVER-FAMILIARITY'.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.