Lubricate rotating gear and ends of spindle (6)
I believe the answer is:
grease
'lubricate' is the definition.
(synonyms)
'rotating gear and ends of spindle' is the wordplay.
'rotating' is an anagram indicator (I've seen this in other clues).
'and' means one lot of letters go next to another.
'ends of' says to hollow out the word (remove centre letters).
'spindle' with its middle taken out is 'se'.
'gear' anagrammed gives 'grea'.
'grea'+'se'='GREASE'
(Other definitions for grease that I've seen before include "Fully aware, astonished" , "Fat, film" , "Lubricate - musical" , "Musical animal fat?" , "Musical - lubricant" .)