Idiot taking millions out of service (3)
I believe the answer is:
ass
'idiot' is the definition.
(thesaurus)
'millions out of service' is the wordplay.
'millions' becomes 'm' (abbreviation).
'out of' suggests deleting specific letters.
'service' becomes 'mass' (I've seen this in other clues).
'mass' with 'm' taken out is 'ASS'.
'taking' is the link.
(Other definitions for ass that I've seen before include "One in Bible spoke" , "Trump's behind" , "Stupid fellow" , "Hardy and sure-footed animal" , "One easily had" .)