Back inside declare a recess (4)
I believe the answer is:
rear
'back' is the definition.
('rear' can be a synonym of 'back')
'inside declare a recess' is the wordplay.
'inside' indicates the answer is hidden within the clue.
'REAR' is hidden within 'declare a recess'.
(Other definitions for rear that I've seen before include "Back; bring up (young)" , "Bring up or stand up on hind legs" , "Foster" , "Jump" , "Hind part" .)