Jailbird and French cop facing tense clash (8)
I believe the answer is:
conflict
'clash' is the definition.
(I've seen this before)
'jailbird and french cop facing tense' is the wordplay.
'jailbird' becomes 'con' (I've seen this in other clues).
'and' means one lot of letters go next to another.
'french cop' becomes 'flic' (I've seen this in other clues).
'facing' is a charade indicator (letters next to each other).
'tense' becomes 't' (abbreviation used in many dictionaries).
'con'+'flic'+'t'='CONFLICT'
(Other definitions for conflict that I've seen before include "Difference of opinion, dispute" , "Discord, contention" , "Strife and struggle" , "Contest, strife" , "Fracas" .)