Current cricketer’s runs welcomed by side (10)
I believe the answer is:
'current' is the definition.
(current of air or water caused by a vehicle)
'cricketer's runs welcomed by side' is the wordplay.
'cricketer's' becomes 'slip's' (position in cricket).
'runs' becomes 'r' (cricket abbreviation).
'welcomed by' means one lot of letters goes inside another (I've seen this in other clues).
'side' becomes 'team' (I've seen this before).
'r' put inside 'team' is 'tream'.
(Other definitions for slipstream that I've seen before include "Draught" , "Aerodynamic effect" , "Air behind a moving vehicle" , "Lams priest (anag.)" , "Air driven back by a propeller" .)