At work, heavy breather is good girl on phone (5-6)
I believe the answer is:
glass-blower
'at work heavy breather' is the definition.
I can't judge whether this defines the answer.
'good girl on phone' is the wordplay.
'good' becomes 'g' (abbreviation).
'girl' becomes 'lass' (lass can informally mean a girl).
'on' says to put letters next to each other.
'phone' becomes 'blower' (informal term for telephone).
'g'+'lass'+'blower'='GLASS-BLOWER'
'is' is the link.
Can you help me to learn more?
(Another definition for glass-blower that I've seen is " Former of bottles, etc".)