Coach starts to execute slow smooth stroke (6)
I believe the answer is:
caress
'stroke' is the definition.
(I know that caress is a type of stroke)
'coach starts to execute slow smooth' is the wordplay.
'coach' becomes 'car' (as in a train coach or car).
'starts to' indicates taking the first letters.
The initial letters of 'execute slow smooth' is 'ess'.
'car'+'ess'='CARESS'
(Other definitions for caress that I've seen before include "pet" , "Stroke lightly in a loving manner" , "pet[s]" , "Embrace with affection" , "Pat" .)