Masses hit oil pool with no time to deviate (3,6)
I believe the answer is:
hoi polloi
'masses' is the definition.
(thesaurus)
'hit oil pool with no time to deviate' is the wordplay.
'with no' indicates named letters should be taken away.
'time' becomes 't'.
'to deviate' is an anagram indicator.
'hit'+'oil'+'pool'='hitoilpool'
'hitoilpool' with 't' taken out is 'hioilpool'.
'hioilpool' anagrammed gives 'HOI POLLOI'.
(Other definitions for hoi polloi that I've seen before include "The common people generally" , "commoners" , "vulgar rabble" , "Plebs" , "The common people - in Greece" .)