Elbow bent under (5)
I believe the answer is:
below
'under' is the definition.
(synonyms)
'elbow bent' is the wordplay.
'bent' is an anagram indicator.
'elbow' with letters rearranged gives 'BELOW'.
(Other definitions for below that I've seen before include "Not worthy of" , "on earth" , "Subordinate to" , "Inferior" , "Underneath" .)