Help a relative into position (10)
I believe the answer is:
assistance
'help' is the definition.
(synonyms)
'a relative into position' is the wordplay.
'relative' becomes 'sis' (short for sister).
'into' is an insertion indicator.
'position' becomes 'stance' (stance is a kind of position).
'sis' put into 'stance' is 'ssistance'.
'a'+'ssistance'='ASSISTANCE'
(Other definitions for assistance that I've seen before include "Aid" , "Support" , "Help" .)