The girl and I get on with the job (7)
I believe the answer is:
mission
'the job' is the definition.
(a mission is a job or task)
'the girl and i get on' is the wordplay.
'the girl' becomes 'miss' (term of address for an unmarried woman).
'and' means one lot of letters go next to another.
'get' means one lot of letters go next to another.
'miss'+'i'+'on'='MISSION'
'with' acts as a link.
(Other definitions for mission that I've seen before include "religious establishment" , "In religious campaign" , "Ministry sent by a church to spread its teaching" , "important business" , "Important assignment" .)