Dad succeeded inflating tyre: delightful! (9)

'delightful' is the definition.
Both the definition and answer are adjectives. Perhaps you can see an association between them that I can't see?

'dad succeeded inflating tyre' is the wordplay.
I cannot quite understand how this works, but
'dad' could be 'pa' (both can mean one's father) and 'pa' is located in the answer.
'succeeded' could be 's' (genealogical abbreviation) and 's' is located in the answer.
'tyre' could be 'radial' (radial is a kind of tyre) and 'radial' is found within the leftover letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?