Raise barrel and lock for support (8)
I believe the answer is:
buttress
'support' is the definition.
(buttress is a kind of support)
'raise barrel and lock' is the wordplay.
'raise' is a reversal indicator.
'barrel' becomes 'tub' (I've seen this before).
'and' says to put letters next to each other.
'lock' becomes 'tress' (both can mean a piece of hair).
'tub' backwards is 'but'.
'but'+'tress'='BUTTRESS'
'for' acts as a link.
(Other definitions for buttress that I've seen before include "Stanchion" , "Projecting support for wall" , "Reinforce" , "Pier" , "support for Notre Dame?" .)