A fine corgi — source of delight for one, possibly (3-7)
I believe the answer is:
'possibly' is the definition.
I don't know anything about this answer so I can't judge whether this works.
'a fine corgi source of delight for one' is the wordplay.
I cannot quite understand how this works, but
'a' could be 'an' and 'an' is found in the answer.
'fine' could be 'f' (abbreviation) and 'f' is present in the answer.
'of' could be 'o' and 'o' is located in the answer.
'one' could be 'i' (Roman numeral) and 'i' is present in the answer.
This may be the basis of the clue (or it may be nonsense).