Catchy tune from Jack by the fireplace (6)
I believe the answer is:
jingle
'catchy tune' is the definition.
(I've seen this before)
'jack by the fireplace' is the wordplay.
'jack' becomes 'j' (playing card abbreviation).
'by' means one lot of letters go next to another.
'the fireplace' becomes 'ingle' (I've seen this before).
'j'+'ingle'='JINGLE'
'from' acts as a link.
(Other definitions for jingle that I've seen before include "Song in advert" , "Ditty" , "Tune for TV commercial" , "upset Pickwick" , "Catchy tune in advert" .)