Bring action against flipping London station? Not half (3)
I believe the answer is:
sue
'bring action against' is the definition.
(thesaurus)
'flipping london station? not half' is the wordplay.
'flipping' says the letters should be written in reverse.
'london station?' becomes 'euston' (I've seen this before).
'not half' means to take half the letters.
'euston' cut in half is 'eus'.
'eus' backwards is 'SUE'.
(Other definitions for sue that I've seen before include "Charge" , "Use to take to court" , "Take legal action against (someone), girl's name" , "- - Barker, 19 star" , "Make a case against" .)