Harass in Managua (3)
I believe the answer is:
nag
'harass' is the definition.
(I've seen this in another clue)
'in managua' is the wordplay.
'in' says the answer is hidden in the clue.
'NAG' is hidden within 'managua'.
(Other definitions for nag that I've seen before include "Constantly scold - small horse" , "Ailing horse" , "Badger continually like old horse" , "Jade" , "trouble constantly" .)