sunderland earn 1-0 tyne-wear derby victory against newcastle at the stadium of light .
jermain defoe gives black cats the lead with stunning left-footed volley before half-time .
former tottenham striker scores his third sunderland goal in hard-fought win for the home side .
sunderland boss dick advocaat earns his first tyne-wear derby victory .
black cats are unbeaten in their last seven barclays premier league games against newcastle united .