Content that's essential to Bangladesh (4)
I believe the answer is:
glad
'content' is the definition.
(I've seen this in another clue)
'essential to bangladesh' is the wordplay.
'essential to' indicates a hidden word (letters in the inside or essence of the clue).
'GLAD' can be found hidden inside 'bangladesh'.
'that's' acts as a link.
(Other definitions for glad that I've seen before include "Made up" , "Feeling pleasure" , "bright?" , "Dressy clothes, informally .... rags" , "Happy, pleased" .)