Get by policeman, last in line (4)
I believe the answer is:
cope
'get by' is the definition.
('cope' can be a synonym of 'get by')
'policeman last in line' is the wordplay.
'policeman' becomes 'cop' (I've seen this before).
'last in' says to take the final letters.
The final letter of 'line' is 'e'.
'cop'+'e'='COPE'
(Other definitions for cope that I've seen before include "Survive" , "Deal with, manage ok" , "Handle a situation" , "Priest's cloak; deal (with)" , "special cloak" .)