Authentic ceasefire abandoned by Cuba (4)
I believe the answer is:
true
'authentic' is the definition.
(thesaurus)
'ceasefire abandoned by cuba' is the wordplay.
'ceasefire' becomes 'truce' (I've seen this before).
'abandoned by' indicates named letters should be taken away.
'cuba' becomes 'c'.
'truce' with 'c' taken out is 'TRUE'.
(Other definitions for true that I've seen before include "not showing 12 [DISHONESTY]" , "Accurate, factual" , "Supported by the facts" , "Right; genuine" , "A false alternative?" .)