Match found about convict's body (8)
I believe the answer is:
fuselage
'body' is the definition.
(fuselage is a kind of body)
'match found about convict's' is the wordplay.
'match' becomes 'fusee' (type of flare).
'found about' is an insertion indicator.
'convict' becomes 'lag' (I've seen this before).
'fusee' going around 'lag' is 'FUSELAGE'.
(Other definitions for fuselage that I've seen before include "Main body of aircraft" , "body of fighter?" , "part of plane" , "part of aircraft" , "Long body" .)