Test needs article to be lowered into old pit (7)
I believe the answer is:
examine
'test' is the definition.
(I know that test can be written as examine)
'article to be lowered into old pit' is the wordplay.
'article' becomes 'a' (the indefinite article in English).
'to be lowered into' indicates putting letters inside.
'old' becomes 'ex' (prefix meaning former or onetime).
'pit' becomes 'mine' (mining pit).
'ex'+'mine'='exmine'
'a' going within 'exmine' is 'EXAMINE'.
'needs' acts as a link.
(Other definitions for examine that I've seen before include "Investigate" , "Subject to inspection" , "Set papers" , "Formally question (law)" , "Thoroughly inspect" .)