Ebbing current with return of damage - metal? (7)
I believe the answer is:
wolfram
'metal?' is the definition.
(wolfram is a kind of metal)
'ebbing current with return of damage' is the wordplay.
'ebbing' is a reversal indicator (to ebb can mean to go backwards).
'current' becomes 'flow' (synonyms).
'with' is a charade indicator (letters next to each other).
'return of' shows that the letters should be reversed in order.
'damage' becomes 'mar' (marring is a kind of damaging).
'flow' in reverse letter order is 'wolf'.
'mar' backwards is 'ram'.
'wolf'+'ram'='WOLFRAM'
(Other definitions for wolfram that I've seen before include "elemental" , "hard stuff" , "at no 74, originally" , "Tungsten" , "greyish-white metal" .)