Oddly, setter rang back? (5)
I believe the answer is:
stern
'back?' is the definition.
(stern means the back of a boat)
'oddly setter rang' is the wordplay.
'oddly' means one should take alternating letters (letters in the odd-numbered positions are used).
'setter'+'rang'='setterrang'
The alternate letters of 'setterrang' are 'STERN'.
(Other definitions for stern that I've seen before include "Rigid" , "Inflexible; back" , "Looking severe" , "enforcing submission" , "Dour" .)