Cleaner but untidy head of hair (3)
I believe the answer is:
mop
This could be a double definition.
'cleaner' is the first definition.
(something which 'cleans')
'untidy head of hair' is the second definition.
'mop' can be an answer for 'hair' (mop can mean a mass of hair). I am not sure about the 'untidy head of' bit.
'but' is the link.
Can you help me to learn more?
(Other definitions for mop that I've seen before include "Finish off a task - . . . up" , "Mass of disordered hair" , "Swab" , "Bundle of soft material at end of stick for cleaning" , "Cleaning implement" .)