Doubt short integrated circuit close to spark plugs is faster (7)
I believe the answer is:
quicker
'is faster' is the definition.
('quick' can be similar in meaning to 'fast')
'doubt short integrated circuit close to spark plugs' is the wordplay.
'doubt' becomes 'query' (I've seen this before).
'short' means to remove the last letter.
'integrated circuit' becomes 'ic' (abbreviation in electronics).
'close to' says to take the final letters (the close/ending of).
'plugs' means one lot of letters goes inside another (plug can mean to fill a gap).
The final letter of 'spark' is 'k'.
'query' with its last letter taken away is 'quer'.
'ic'+'k'='ick'
'quer' going around 'ick' is 'QUICKER'.
(Other definitions for quicker that I've seen before include "Faster" , "More speedy" , "More speedily" , "Speedier" .)