Perhaps make short detectives dig endlessly? (6)
I believe the answer is:
distil
'perhaps make short' is the definition.
'detectives dig endlessly?' is the wordplay.
'detectives' becomes 'dis' (Detective Inspectors, DIs).
'dig' becomes 'till' (I've seen this before).
'endlessly?' means to remove the last letter (I've seen 'endlessly' mean this).
'till' with its last letter taken off is 'til'.
'dis'+'til'='DISTIL'
(Other definitions for distil that I've seen before include "Vaporise and condense" , "Evaporate, purify" , "Make alcoholic liquor by heating and cooling process" , "Make more concise" , "Purify (liquid) by heat" .)