View clock's middle cog (7)
I believe the answer is:
opinion
'view' is the definition.
(synonyms)
'clock's middle cog' is the wordplay.
'middle' indicates the central letters.
'cog' becomes 'pinion' (both can mean a mechanical part).
The middle letter of 'clock' is 'o'.
'o'+'pinion'='OPINION'
(Other definitions for opinion that I've seen before include "View held without positive proof" , "Personal belief without proof" , "school of thought" , "thinking" , "'Judgment, view (7)'" .)