Get sentry to go up to guard secluded retreat (4)
I believe the answer is:
nest
'secluded retreat' is the definition.
'nest' can be an answer for 'retreat' (nest is a kind of retreat). I'm unsure of the 'secluded' bit.
'get sentry to go up to guard' is the wordplay.
'to guard' indicates a hidden word (I've seen 'guarding' mean this).
'to go up' says the letters should be written in reverse (I've seen 'going up' mean this).
'tsen' can be found hidden inside 'get sentry'.
'tsen' reversed gives 'NEST'.
Can you help me to learn more?
(Other definitions for nest that I've seen before include "Something found in Chinese soup" , "Stack of tables" , "Structure built by birds" , "Sent to bird's home" , "'Birds in their little . . . . agree'" .)