Very complimentary about girl and boy initially working in furnace conditions? (5-7)
I believe the answer is:
glass-blowing
'working in furnace conditions?' is the definition.
'very complimentary about girl and boy initially' is the wordplay.
'very complimentary' becomes 'glowing'.
'about' means one lot of letters goes inside another.
'girl' becomes 'lass' (lass is a kind of girl**).
'and' says to put letters next to each other.
'initially' suggests taking the first letters.
The first letter of 'boy' is 'b'.
'lass'+'b'='lassb'
'glowing' placed around 'lassb' is 'GLASS-BLOWING'.
(Another definition for glass-blowing that I've seen is " Art of making bottles etc".)