Bear up in the band? (4)
I believe the answer is:
hoop
'the band?' is the definition.
(hoop is a kind of band)
'bear up' is the wordplay.
'bear' becomes 'pooh' (Winnie the Pooh).
'up' says the letters should be written backwards (in down clue: letters go upwards).
'pooh' back-to-front is 'HOOP'.
'in' acts as a link.
(Other definitions for hoop that I've seen before include "Arch used in croquet" , "Circular band; child's toy" , "Rigid circular band" , "Metal ring for croquet and basketball" , "Circlet" .)