Looking up advice on light aircraft (8)
I believe the answer is:
spitfire
'aircraft' is the definition.
(I've seen this before)
'looking up advice on light' is the wordplay.
'looking up' is a reversal indicator (in a down clue, letters go up).
'advice' becomes 'tips' (I've seen this in another clue).
'on' means one lot of letters go next to another.
'light' becomes 'fire'.
'tips' in reverse letter order is 'spit'.
'spit'+'fire'='SPITFIRE'
(Other definitions for spitfire that I've seen before include "Quick-tempered person" , "British warplane" , "WW2 fighter aircraft" , "Ill-tempered sort" , "WWII warplane" .)