In case the article included is the minimum (5)
I believe the answer is:
least
'the minimum' is the definition.
(I've seen this before)
'in case the article included' is the wordplay.
'in case' becomes 'lest' (as in 'lest we forget').
'the article' becomes 'a' (the indefinite article in English).
'included' means one lot of letters goes inside another.
'lest' enclosing 'a' is 'LEAST'.
'is' is the link.
(Other definitions for least that I've seen before include "Lowest amount" , "Smallest in amount or degree" , "Opposite of most" , "Steal (anag)" , "Being lowest in importance - gone stale" .)