Help when one's stuck in position (10)
I believe the answer is:
assistance
'help' is the definition.
(I know that help can be written as assistance)
'when one's stuck in position' is the wordplay.
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'one's' becomes 'i's' (Roman numeral).
'stuck in' indicates putting letters inside.
'position' becomes 'stance' (stance is a kind of position).
'is' inserted into 'stance' is 'sistance'.
'as'+'sistance'='ASSISTANCE'
(Other definitions for assistance that I've seen before include "Help" , "Aid" , "Support" .)