Turn over fine border
I believe the answer is:
flip
'turn over' is the definition.
(synonyms)
'fine border' is the wordplay.
'fine' becomes 'f' (abbreviation).
'border' becomes 'lip' (I've seen this in other clues).
'f'+'lip'='FLIP'
(Other definitions for flip that I've seen before include "Get angry" , "Turn over; over-smart" , "Toss - impertinent" , "Throw a wobbly" , "demanding > alcoholic drink" .)