On retiring, remains a person without influence (6)
I believe the answer is:
nobody
'a person without influence' is the definition.
(I've seen this before)
'on retiring remains' is the wordplay.
'retiring' shows that the letters should be reversed in order.
'remains' becomes 'body' (as in a corpse).
'on' in reverse letter order is 'no'.
'no'+'body'='NOBODY'
(Other definitions for nobody that I've seen before include "Insignificant person" , "Nonentity" , "Cipher" , "Inadequacy of wine" , "Person without influence" .)