Request comes in to get engine part (6)
I believe the answer is:
gasket
'engine part' is the definition.
'request comes in to get' is the wordplay.
'request' becomes 'ask' ('ask' can be a synonym of 'request').
'comes in to' is an insertion indicator.
'ask' placed into 'get' is 'GASKET'.
(Other definitions for gasket that I've seen before include "Tow used for packing a piston" , "Seal between metal faces" , "Packing piece used as seal in metal joint" , "Sealing sheet in an engine" , "Ring for sealing a pipe joint" .)