… Abba or A-ha? Do-re-mi plan scuppered (10)
I believe the answer is:
palindrome
'abba or a-ha?' is the definition.
(Abba and A-ha are palindromes)
'do-re-mi plan scuppered' is the wordplay.
'scuppered' indicates an anagram ('scuppered' can mean wrecked).
'do'+'re'+'mi'+'plan'='doremiplan'
'doremiplan' anagrammed gives 'PALINDROME'.
(Other definitions for palindrome that I've seen before include "Word reading the same backwards and forwards" , "Word(s) reading the same forward and back" , "Word like the Indian language "Malayalam", for instance" , "Hannah, perhaps" , "E.g. mum, dad" .)