Engineers checked piece on back of engine emitting fumes (7)
I believe the answer is:
reeking
'emitting fumes' is the definition.
'reeking' can be an answer for 'emitting' (reeking is a kind of emiting). I am not certain of the 'fumes' bit.
'engineers checked piece on back of engine' is the wordplay.
'engineers' becomes 're' (Royal Engineers).
'checked piece' becomes 'king' (king is a kind of chess piece. I am not sure about the 'checked' bit.).
'on' is a charade indicator (letters next to each other).
'back of' suggests the final letters.
The final letter of 'engine' is 'e'.
'king' put after 'e' is 'eking'.
're'+'eking'='REEKING'
Can you help me to learn more?
(Other definitions for reeking that I've seen before include "Foul smelling" , "With a very unpleasant smell" , "Stinking" , "Emitting smoke" , "Giving off a strong smell" .)