He'd tampered with NHS headings, such arrogant disregard for others! (4-10)

'he'd tampered with nhs headings such arrogant disregard for others' is the definition.
The definition suggests a singular noun which matches the answer.

'he'd tampered with' is the wordplay.
I cannot really see how this works, but
'with' could be 'and' and 'and' is present in the answer.
'he'd' could be 'hed' and 'hed' is located in the leftover letters.
The remaining letters 'highness' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...

Can you help me to learn more?