[to work] at the sharp end

The sharp end (mainly British & Australian) means involved in the area of any activity where there is most difficulty, competition, danger &c/ the most difficult part where problems are likely to happen (usually + of )
-- She enjoys the challenge of being at the sharp end of investment banking.
From a copy of a medical article: -Nurses at the “Sharp End” of Patient Care.:down:

First try: (Εργάζεται σε χώρο/τομέα/εργασία που αποτελεί την) αιχμή του δόρατος. One could also use στην πρώτη γραμμή (at the front line).

Η αιχμή του δόρατος αποδίδει το spearhead και, για να είναι ακριβής η έκφραση, πρέπει να έχει σχέση με κάποια πρωτοβουλία, κάποια «επίθεση».

Το sharp end έχει βγει από αργκοτική έκφραση για την πλώρη του πλοίου και η αρχική του μεταφορική σημασία είναι η πρώτη γραμμή, που λέει και ο drsiebenmal.

OED:
1976 New Scientist 28 Oct. 230/2 Within a few months I was appointed financial controller.‥ But I still wasn't at the sharp end.    
1980 A. Price Hour of Donkey ii. 36 The distant sound of bombing indicated that he was very close to the {sharp end} of the war.
ODE:
1 the most important or influential part of an activity or process: he was born at the sharp end of history
- the most risky or unpleasant part of a system or activity: businessmen are at the sharp end of the recession