Lights not working - awful outside! (5)
I believe the answer is:
offal
'lights' is the definition.
(I've seen this before)
'not working awful outside' is the wordplay.
'not working' becomes 'off' (I've seen this before).
'outside' means to remove the middle letters.
'awful' with its middle removed is 'al'.
'off'+'al'='OFFAL'
(Other definitions for offal that I've seen before include "Liver, kidney, etc, as food" , "Edible animal viscera" , "Edible innards" , "Putting cargo on (ship)" , "Bits of waste meat" .)