Spot second article in French (4)
I believe the answer is:
mole
'spot' is the definition.
(spot or blemish on the skin)
'second article in french' is the wordplay.
'second' becomes 'mo' (both are short periods of time).
'article in french' becomes 'le' ('the', the definite article in French).
'mo'+'le'='MOLE'
(Other definitions for mole that I've seen before include "sauce" , "Infiltrator" , "Tunneller" , "Spy - creator of hills?" , "Agent; breakwater" .)