Base of guerrilla den in Ecuador revealed (7)
I believe the answer is:
adenine
'base' is the definition.
(I know that adenine is a type of purine)
'guerrilla den in ecuador revealed' is the wordplay.
'revealed' indicates the answer is hidden within the clue (I've seen 'reveals' mean this).
'ADENINE' can be found hidden inside 'guerrilla den in ecuador'.
'of' acts as a link.
(Other definitions for adenine that I've seen before include "Biochemical compound" , "One of the four bases of DNA" , "Basis of DNA" .)