Power tool put back beside table, initially requiring support (7)
I believe the answer is:
reliant
'requiring support' is the definition.
(relying on another person's support)
'power tool put back beside table initially' is the wordplay.
'power tool' becomes 'nailer' (tool for inserting nails).
'put back' is a reversal indicator.
'beside' says to put letters next to each other (I've seen this in other clues).
'initially' indicates taking the first letters.
The first letter of 'table' is 't'.
'nailer' in reverse letter order is 'relian'.
'relian'+'t'='RELIANT'
(Other definitions for reliant that I've seen before include "Dependent (on person)" , "Dependent - latrine (anag)" , "car firm" , "Depending on another for support" , "Trusting" .)