Troubled ex-Marine given drug test again (2-7)
I believe the answer is:
re-examine
'test again' is the definition.
(to examine or test again)
'troubled ex-marine given drug' is the wordplay.
'troubled' indicates an anagram.
'given' is an insertion indicator.
'drug' becomes 'e' (E is another name for ecstasy).
'ex'+'marine'='exmarine'
'exmarine' anagrammed gives 'rexamine'.
'rexamine' placed around 'e' is 'RE-EXAMINE'.
(Other definitions for re-examine that I've seen before include "Look at again" , "Study further" , "Investigate again" .)