About one thousand different paint drums (7)
I believe the answer is:
timpani
'drums' is the definition.
(type of drums)
'about one thousand different paint' is the wordplay.
'about' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'thousand' becomes 'm' (Roman numeral for a thousand).
'different' is an anagram indicator.
'i'+'m'='im'
'paint' is an anagram of 'tpani'.
'im' going within 'tpani' is 'TIMPANI'.
(Other definitions for timpani that I've seen before include "orchestra members" , "Something making drumming noise" , "Percussion instrument" , "> kitchen equipment?" , "Main pit (anag) - drums" .)