The old were worried about the first graveyard resident (7)

'graveyard resident' is the definition.
I don't know anything about this answer so I can't judge whether this works.

'the old were worried about the' is the wordplay.
'the old' becomes 'ye' (resembles a historical spelling of 'the').
'worried' is an anagram indicator (worry can mean to interfere with or disturb).
'about' means one lot of letters goes inside another.
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'were' with letters rearranged gives 'wree'.
'wree' placed around 't' is 'wtree'.
'ye'+'wtree'='YEWTREE'

'first' acts as a link.

Can you help me to learn more?