After a drop of Hermitage, old boy wanting seconds where food's prepared (4)
I believe the answer is:
hobs
'where food's prepared' is the definition.
(cooking appliance)
'after a drop of hermitage old boy wanting seconds' is the wordplay.
'after' says to put letters next to each other.
'a drop of' indicates taking the first letters.
'old boy' becomes 'ob' (abbreviation).
'wanting' says to put letters next to each other.
'seconds' becomes 's'.
The initial letter of 'hermitage' is 'h'.
'h' next to 'ob' is 'hob'.
'hob'+'s'='HOBS'
(Another definition for hobs that I've seen is " Hot plates".)