Call during play originally mounted by French department (6)
I believe the answer is:
misere
'call during play' is the definition.
(type of call made in poker)
'originally mounted by french department' is the wordplay.
'originally' says to take the initial letters.
'by' says to put letters next to each other.
'french department' becomes 'isere' (Isere is a department of France).
The first letter of 'mounted' is 'm'.
'm'+'isere'='MISERE'
(Other definitions for misere that I've seen before include "Solo whist no-tricks bid" , "Card-player's call" , "Taking no tricks" , "undertaking to take no tricks" .)