Sits, as unsteady? Help! (6)
I believe the answer is:
assist
'help' is the definition.
(assisting is a kind of helping)
'sits as unsteady?' is the wordplay.
'unsteady?' is an anagram indicator (I've seen 'unsteady' mean this).
'sits'+'as'='sitsas'
'sitsas' with letters rearranged gives 'ASSIST'.
(Other definitions for assist that I've seen before include "Aid, abet" , "providing help?" , "Be helpful to" , "Give a hand to" , "Help, lend a hand" .)