Bring back lean source of iron? (7)
I believe the answer is:
restore
'bring back' is the definition.
(synonyms)
'lean source of iron?' is the wordplay.
'lean' becomes 'rest' (I've seen this before).
'source of iron?' becomes 'ore' (I've seen this in another clue).
'rest'+'ore'='RESTORE'
(Other definitions for restore that I've seen before include "Return to original condition" , "Renew, repair; give back" , "Bring back to health" , "Repair, put back" , "Bring back; renovate" .)