Trinidad's leader gets on top of cause for betrayal (7)
I believe the answer is:
treason
'for betrayal' is the definition.
(synonyms)
'trinidad's leader gets on top of cause' is the wordplay.
'leader' says to take the initial letters.
'gets' means one lot of letters go next to another.
'on' becomes 're' ('on' can be mean 'with reference to').
'top of cause' becomes 'ason' (I can't justify this - if you can you should believe this answer much more).
The initial letter of 'trinidad' is 't'.
't'+'re'+'ason'='TREASON'
Can you help me to learn more?
(Other definitions for treason that I've seen before include "Betrayal of one's nation" , "Crime agains one's country" , "Crime of treachery against the state" , "Crime of disloyalty" , "rebellion" .)