Had doubts about speed cuts working (9)
I believe the answer is:
suspected
'had doubts' is the definition.
'speed cuts working' is the wordplay.
'working' is an anagram indicator.
'speed'+'cuts'='speedcuts'
'speedcuts' is an anagram of 'SUSPECTED'.
'about' is the link.
(Other definitions for suspected that I've seen before include "mistrusted" , "Believed to be guilty but without proof" , "Felt" , "Imagined to be true" , "Believed likely or distrusted" .)