Comedian has a race with European power (7)
I believe the answer is:
wattage
'power' is the definition.
(I know that wattage is a type of power)
'comedian has a race with european' is the wordplay.
'comedian' becomes 'wag' (I've seen this before).
'has' is an insertion indicator.
'race' becomes 'tt'.
'with' says to put letters next to each other.
'european' becomes 'E' (abbreviation e.g. EU).
'a'+'tt'='att'
'wag' going around 'att' is 'wattag'.
'wattag'+'e'='WATTAGE'
(Other definitions for wattage that I've seen before include "Light bulb power rating" , "Amount of electrical power" , "Electrical power rating" .)