Contact this man if the motor starts to hesitate (8)
I believe the answer is:
engineer
'contact this man if' is the definition.
The answer and definition can be both people as well as being singular nouns.
Maybe there's a link between them I don't understand?
'motor starts to hesitate' is the wordplay.
'motor' becomes 'engine' (engine is a kind of motor).
'starts' means to remove the last letter.
'to hesitate' becomes 'eer' (I can't explain this - if you can you should give a lot more credence to this answer).
'engine' with its last letter taken away is 'engin'.
'engin'+'eer'='ENGINEER'
'the' is the link.
Can you help me to learn more?
(Other definitions for engineer that I've seen before include "Cleverly bring about" , "Effect this professional man" , "Bring about (an event); technologist" , "One who designs, makes or runs motors" , "Plot" .)