“Like a bone?” First of underfed Labradors raced back (5)
I believe the answer is:
ulnar
'like a bone?' is the definition.
I can't tell whether this definition defines the answer.
'first of underfed labradors raced back' is the wordplay.
'first of' indicates taking the first letters.
'raced' becomes 'ran' (running is a kind of racing).
'back' is a reversal indicator.
The first letters of 'underfed labradors' is 'ul'.
'ran' in reverse letter order is 'nar'.
'ul'+'nar'='ULNAR'
Can you help me to learn more?
(Other definitions for ulnar that I've seen before include "Relating to a particular arm bone" , "Relating to one of the bones of the forearm" , "Relating to a bone in the forearm" , "of certain bones" .)