Condense detective's suspect list (6)
I believe the answer is:
distil
'condense' is the definition.
(I know that condense can be written as distil)
'detective's suspect list' is the wordplay.
'detective' becomes 'di' (Detective Inspector abbreviation).
'suspect' is an anagram indicator (a suspicious or unusual spelling).
'list' anagrammed gives 'stil'.
'di'+'stil'='DISTIL'
(Other definitions for distil that I've seen before include "Treat substance through heating and cooling to extract an essence - whiskey?" , "Purify (whisky, for example)" , "Make, eg, whisky" , "Evaporate, purify" , "Purify and condense liquid" .)