Behind the right-hand auricle (4)
I believe the answer is:
rear
'behind' is the definition.
(synonyms)
'the right-hand auricle' is the wordplay.
'the right-hand' becomes 'r' (this might be a standard abbreviation of which I'm unaware).
'auricle' becomes 'ear' (synonyms).
'r'+'ear'='REAR'
Can you help me to learn more?
(Other definitions for rear that I've seen before include "Bring up - back end" , "Bring up and care for" , "Bring up - the tail" , "Hind part" , "Of horse, rise up on hind legs" .)